MIT-OCW-Transcripts / -GXIkn_ecKY.txt
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hi everybody I'm rumen and today I will
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hi everybody I'm rumen and today I will
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hi everybody I'm rumen and today I will
talk about three things optical trapping
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talk about three things optical trapping
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talk about three things optical trapping
the Boltzmann constant and Brownian
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the Boltzmann constant and Brownian
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the Boltzmann constant and Brownian
motion the goal of the lab is to extract
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motion the goal of the lab is to extract
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motion the goal of the lab is to extract
Boltzmann's constant out of Brownian
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Boltzmann's constant out of Brownian
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Boltzmann's constant out of Brownian
motion and there are two key components
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motion and there are two key components
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motion and there are two key components
to think about first one is the
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to think about first one is the
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to think about first one is the
Boltzmann constant which is prevalent in
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Boltzmann constant which is prevalent in
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Boltzmann constant which is prevalent in
different types of science for example
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different types of science for example
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different types of science for example
we can have it in biophysics where
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we can have it in biophysics where
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we can have it in biophysics where
people use the Boltzmann constant to try
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people use the Boltzmann constant to try
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people use the Boltzmann constant to try
to understand forces in a cellular level
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to understand forces in a cellular level
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to understand forces in a cellular level
we have it in thermodynamics with the
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we have it in thermodynamics with the
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we have it in thermodynamics with the
famous equipartition theorem how does
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famous equipartition theorem how does
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famous equipartition theorem how does
this relate to the Brownian motion the
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this relate to the Brownian motion the
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this relate to the Brownian motion the
key thing is to think about length
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key thing is to think about length
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key thing is to think about length
scales Brownian motion is relevant in
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scales Brownian motion is relevant in
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scales Brownian motion is relevant in
terms of microns and at the same time if
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terms of microns and at the same time if
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terms of microns and at the same time if
we look at the cellular level for
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we look at the cellular level for
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we look at the cellular level for
example if we look at our hair we have
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example if we look at our hair we have
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example if we look at our hair we have
micron sized hair all right so there are
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micron sized hair all right so there are
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micron sized hair all right so there are
different ways to measure the
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different ways to measure the
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different ways to measure the
Boltzmann's constant some people measure
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Boltzmann's constant some people measure
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Boltzmann's constant some people measure
the speed of sound in argon gas others
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the speed of sound in argon gas others
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the speed of sound in argon gas others
do optical trapping in air we will do
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do optical trapping in air we will do
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do optical trapping in air we will do
slightly different optical trapping as
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slightly different optical trapping as
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slightly different optical trapping as
you will see but the consensus among the
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you will see but the consensus among the
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you will see but the consensus among the
scientific community is that it is
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scientific community is that it is
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scientific community is that it is
challenging our plan is to prepare
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challenging our plan is to prepare
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challenging our plan is to prepare
Brownian particles and control their
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Brownian particles and control their
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Brownian particles and control their
Brownian motion we take glass beads of
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Brownian motion we take glass beads of
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Brownian motion we take glass beads of
their spherical glass beads of diameter
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their spherical glass beads of diameter
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their spherical glass beads of diameter
of 3.2 microns and the main to is to
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of 3.2 microns and the main to is to
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of 3.2 microns and the main to is to
concentrate a highly focused lasers on
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concentrate a highly focused lasers on
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concentrate a highly focused lasers on
top of these beads there's interesting
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top of these beads there's interesting
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top of these beads there's interesting
physics going on light carries momentum
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physics going on light carries momentum
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physics going on light carries momentum
versa generates force we have that the
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versa generates force we have that the
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versa generates force we have that the
net gradient force opposes the motion of
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net gradient force opposes the motion of
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net gradient force opposes the motion of
the beam while the net scattering force
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the beam while the net scattering force
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the beam while the net scattering force
goes along the motion of the beam and
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goes along the motion of the beam and
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goes along the motion of the beam and
when these two forces balance each other
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when these two forces balance each other
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when these two forces balance each other
we have a beat that is at the center
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we have a beat that is at the center
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we have a beat that is at the center
when you push this beat a little bit to
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when you push this beat a little bit to
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when you push this beat a little bit to
the left or to the right then we have
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the left or to the right then we have
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the left or to the right then we have
that the gradient forces are pulling
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that the gradient forces are pulling
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that the gradient forces are pulling
back in the center and essentially we
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back in the center and essentially we
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back in the center and essentially we
observe a simple harmonic motion in a
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observe a simple harmonic motion in a
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observe a simple harmonic motion in a
more concrete example what we did is we
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more concrete example what we did is we
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more concrete example what we did is we
took samples and we can find everything
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took samples and we can find everything
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took samples and we can find everything
into a two-dimensional plane this is
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into a two-dimensional plane this is
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into a two-dimensional plane this is
very important we have two directions
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very important we have two directions
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very important we have two directions
the X direction in the Y direction for
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the X direction in the Y direction for
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the X direction in the Y direction for
the beads we put them into water and
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the beads we put them into water and
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the beads we put them into water and
source of Brownian motion comes from the
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source of Brownian motion comes from the
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source of Brownian motion comes from the
collisions between our bead with the
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collisions between our bead with the
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collisions between our bead with the
molecules into the water
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molecules into the water
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molecules into the water
these are thermal collisions that
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these are thermal collisions that
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these are thermal collisions that
generate Brownian motion as you can see
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generate Brownian motion as you can see
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generate Brownian motion as you can see
this lonely beat has its Brownian motion
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this lonely beat has its Brownian motion
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this lonely beat has its Brownian motion
what's interesting is when we shine
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what's interesting is when we shine
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what's interesting is when we shine
light on top of a beat we trap this beat
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light on top of a beat we trap this beat
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light on top of a beat we trap this beat
and we can find the Brownian motion so
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and we can find the Brownian motion so
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and we can find the Brownian motion so
it's feasible to measure the motion and
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it's feasible to measure the motion and
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it's feasible to measure the motion and
the theory behind this is very beautiful
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the theory behind this is very beautiful
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the theory behind this is very beautiful
it's about the equipartition theorem
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it's about the equipartition theorem
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it's about the equipartition theorem
which relates the kinetic energy coming
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which relates the kinetic energy coming
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which relates the kinetic energy coming
from the simple harmonic motion on the
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from the simple harmonic motion on the
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from the simple harmonic motion on the
left-hand side with the thermal energy
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left-hand side with the thermal energy
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left-hand side with the thermal energy
of due to the degrees of freedom now let
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of due to the degrees of freedom now let
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of due to the degrees of freedom now let
us recall that we have a two-dimensional
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us recall that we have a two-dimensional
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us recall that we have a two-dimensional
confinement so we have a direction in X
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confinement so we have a direction in X
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confinement so we have a direction in X
and direction in Y so it means that in
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and direction in Y so it means that in
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and direction in Y so it means that in
each of the directions we have one
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each of the directions we have one
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each of the directions we have one
degree of freedom which is correlated
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degree of freedom which is correlated
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degree of freedom which is correlated
with this equipartition theorem now an
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with this equipartition theorem now an
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with this equipartition theorem now an
interesting thing about the statistical
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interesting thing about the statistical
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interesting thing about the statistical
motion of the molecules is that we have
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motion of the molecules is that we have
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motion of the molecules is that we have
the simple harmonic motion however the
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the simple harmonic motion however the
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the simple harmonic motion however the
things are moving into water so there is
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things are moving into water so there is
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things are moving into water so there is
a drag force that dominates so we
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a drag force that dominates so we
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a drag force that dominates so we
simplify the left hand side what is very
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simplify the left hand side what is very
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simplify the left hand side what is very
interesting is the F factor which comes
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interesting is the F factor which comes
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interesting is the F factor which comes
from the collisions between the beat
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from the collisions between the beat
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from the collisions between the beat
with the molecules this generates
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with the molecules this generates
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with the molecules this generates
forcing and driving of the simple
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forcing and driving of the simple
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forcing and driving of the simple
harmonic motion I like to point out one
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harmonic motion I like to point out one
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harmonic motion I like to point out one
thing about the scales of the forces we
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thing about the scales of the forces we
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thing about the scales of the forces we
have Pico Newton's which is relevant for
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have Pico Newton's which is relevant for
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have Pico Newton's which is relevant for
optical trapping and for Brownian motion
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optical trapping and for Brownian motion
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optical trapping and for Brownian motion
this is the first observation that we
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this is the first observation that we
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this is the first observation that we
did and actually Einstein this operation
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did and actually Einstein this operation
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did and actually Einstein this operation
a long time ago he observed the white
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a long time ago he observed the white
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a long time ago he observed the white
noise essentially the collisions they
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noise essentially the collisions they
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noise essentially the collisions they
generate uncorrelated forcing and we can
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generate uncorrelated forcing and we can
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generate uncorrelated forcing and we can
think of it as something that is not
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think of it as something that is not
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think of it as something that is not
biased with any distribution is just
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biased with any distribution is just
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biased with any distribution is just
uniform as you can see on these slides
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uniform as you can see on these slides
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uniform as you can see on these slides
we have the position plotted in terms of
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we have the position plotted in terms of
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we have the position plotted in terms of
and it exhibits a uniform distribution
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and it exhibits a uniform distribution
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and it exhibits a uniform distribution
of the spectrum another thing that I
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of the spectrum another thing that I
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of the spectrum another thing that I
would like to point out is to look at
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would like to point out is to look at
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would like to point out is to look at
this plot of fluctuations in X&Y and the
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this plot of fluctuations in X&Y and the
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this plot of fluctuations in X&Y and the
power which is linear with the current
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power which is linear with the current
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power which is linear with the current
of the lasers as you can see as the
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of the lasers as you can see as the
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of the lasers as you can see as the
power becomes big this means that we are
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power becomes big this means that we are
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power becomes big this means that we are
trapping more so we have less
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trapping more so we have less
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trapping more so we have less
fluctuations which is something as
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fluctuations which is something as
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fluctuations which is something as
expected all right so let's figure out
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expected all right so let's figure out
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expected all right so let's figure out
what we want to do with this lab we have
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what we want to do with this lab we have
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what we want to do with this lab we have
the equipartition theorem and
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the equipartition theorem and
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the equipartition theorem and
essentially we have three components
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essentially we have three components
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essentially we have three components
that we would like to measure in order
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that we would like to measure in order
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that we would like to measure in order
to extract Kb we need to find the
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to extract Kb we need to find the
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to extract Kb we need to find the
fluctuations which I just presented to
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fluctuations which I just presented to
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fluctuations which I just presented to
you we need to find the stiffness
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you we need to find the stiffness
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you we need to find the stiffness
coefficient alpha which is related to
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coefficient alpha which is related to
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coefficient alpha which is related to
the spring constant of motion and then
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the spring constant of motion and then
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the spring constant of motion and then
we need to measure the temperature T the
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we need to measure the temperature T the
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we need to measure the temperature T the
apparatus that we use has two main
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apparatus that we use has two main
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apparatus that we use has two main
components the two components are
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components the two components are
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components the two components are
concerned with the two types of light
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concerned with the two types of light
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concerned with the two types of light
that we use in our experiment we use a
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that we use in our experiment we use a
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that we use in our experiment we use a
laser that shines on top of the confined
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laser that shines on top of the confined
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laser that shines on top of the confined
two-dimensional samples and tries to
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two-dimensional samples and tries to
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two-dimensional samples and tries to
trap a beat the scatter light from the
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trap a beat the scatter light from the
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trap a beat the scatter light from the
laser goes into a QP D a quadrant photo
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laser goes into a QP D a quadrant photo
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laser goes into a QP D a quadrant photo
detector which is an ultra-fast camera
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detector which is an ultra-fast camera
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detector which is an ultra-fast camera
that manages to quickly digitalize the
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that manages to quickly digitalize the
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that manages to quickly digitalize the
content and give us the position of the
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content and give us the position of the
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content and give us the position of the
scattered light so when we trap the beat
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scattered light so when we trap the beat
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scattered light so when we trap the beat
we know where it is by observing the
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we know where it is by observing the
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we know where it is by observing the
feedback from the QPD the other
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feedback from the QPD the other
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feedback from the QPD the other
interesting part of the apparatus is the
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interesting part of the apparatus is the
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interesting part of the apparatus is the
LED light which illuminates the sample
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LED light which illuminates the sample
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LED light which illuminates the sample
and then it brings it to the CCD camera
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and then it brings it to the CCD camera
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and then it brings it to the CCD camera
and this is very important so the CCD
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and this is very important so the CCD
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and this is very important so the CCD
camera is very slow it cannot measure
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camera is very slow it cannot measure
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camera is very slow it cannot measure
Brownian motion what it can do is it can
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Brownian motion what it can do is it can
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Brownian motion what it can do is it can
tell us where are the beats it can allow
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tell us where are the beats it can allow
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tell us where are the beats it can allow
us to look at the water and like find
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us to look at the water and like find
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us to look at the water and like find
the beats we want to trap so these two
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the beats we want to trap so these two
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the beats we want to trap so these two
components in combination are crucial
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components in combination are crucial
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components in combination are crucial
for the success of our research there is
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for the success of our research there is
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for the success of our research there is
interesting electronics coming behind
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interesting electronics coming behind
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interesting electronics coming behind
this essentially the signals from the
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this essentially the signals from the
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this essentially the signals from the
QPD and from the stage position where we
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QPD and from the stage position where we
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QPD and from the stage position where we
put our sample are
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put our sample are
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put our sample are
given in terms of volts so a natural
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given in terms of volts so a natural
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given in terms of volts so a natural
question that arises is how are we going
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question that arises is how are we going
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question that arises is how are we going
to remember what is important there are
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to remember what is important there are
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to remember what is important there are
two important things that would like to
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two important things that would like to
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two important things that would like to
keep track of two positions the first
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keep track of two positions the first
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keep track of two positions the first
one is the position of the stage that
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one is the position of the stage that
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one is the position of the stage that
gives us a relative point of
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gives us a relative point of
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gives us a relative point of
consideration and the second one is the
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consideration and the second one is the
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consideration and the second one is the
position of the QPD which as you can
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position of the QPD which as you can
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position of the QPD which as you can
recall it measures the place of the beat
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recall it measures the place of the beat
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recall it measures the place of the beat
that we have trapped these inputs are
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that we have trapped these inputs are
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that we have trapped these inputs are
given in terms of volts so the natural
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given in terms of volts so the natural
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given in terms of volts so the natural
thing to do is to find a calibration
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thing to do is to find a calibration
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thing to do is to find a calibration
that converts these volts into actual
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that converts these volts into actual
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that converts these volts into actual
distances here you can see how we do
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distances here you can see how we do
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distances here you can see how we do
this we plot the stage X or position you
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this we plot the stage X or position you
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this we plot the stage X or position you
can we can plot the stage Y it's
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can we can plot the stage Y it's
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can we can plot the stage Y it's
completely analogous to the to the QPD
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completely analogous to the to the QPD
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completely analogous to the to the QPD
positions here and the conversion factor
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positions here and the conversion factor
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positions here and the conversion factor
hides along these slopes here well as
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hides along these slopes here well as
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hides along these slopes here well as
you can see we have two different slopes
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you can see we have two different slopes
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you can see we have two different slopes
here with different absolute values so
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here with different absolute values so
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here with different absolute values so
this type of measurement is prone to
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this type of measurement is prone to
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this type of measurement is prone to
errors how we approach this problem is
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errors how we approach this problem is
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errors how we approach this problem is
that we fought by choosing more data
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that we fought by choosing more data
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that we fought by choosing more data
points and trying to increase the
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points and trying to increase the
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points and trying to increase the
statistic thus hopefully reducing the
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statistic thus hopefully reducing the
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statistic thus hopefully reducing the
systematics of this measurement the
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systematics of this measurement the
align:start position:0%
systematics of this measurement the
second step is to start getting the
align:start position:0%
second step is to start getting the
align:start position:0%
second step is to start getting the
components that we need in order to
align:start position:0%
components that we need in order to
align:start position:0%
components that we need in order to
extract KB is to measure the stiffness
align:start position:0%
extract KB is to measure the stiffness
align:start position:0%
extract KB is to measure the stiffness
coefficient alpha now the main idea is
align:start position:0%
coefficient alpha now the main idea is
align:start position:0%
coefficient alpha now the main idea is
to take the equation of motion and to
align:start position:0%
to take the equation of motion and to
align:start position:0%
to take the equation of motion and to
make a Fourier transform in order to get
align:start position:0%
make a Fourier transform in order to get
align:start position:0%
make a Fourier transform in order to get
the positions in terms of frequencies
align:start position:0%
the positions in terms of frequencies
align:start position:0%
the positions in terms of frequencies
there is mathematics behind this and
align:start position:0%
there is mathematics behind this and
align:start position:0%
there is mathematics behind this and
essentially the power spectral
align:start position:0%
essentially the power spectral
align:start position:0%
essentially the power spectral
distribution and as the distribution of
align:start position:0%
distribution and as the distribution of
align:start position:0%
distribution and as the distribution of
this motion here that we expect obtains
align:start position:0%
this motion here that we expect obtains
align:start position:0%
this motion here that we expect obtains
this form here from where we can extract
align:start position:0%
this form here from where we can extract
align:start position:0%
this form here from where we can extract
the characteristic frequency F naught
align:start position:0%
the characteristic frequency F naught
align:start position:0%
the characteristic frequency F naught
and F naught gives us alpha which is
align:start position:0%
and F naught gives us alpha which is
align:start position:0%
and F naught gives us alpha which is
what we really need this is a log-log
align:start position:0%
what we really need this is a log-log
align:start position:0%
what we really need this is a log-log
plot as you can see here another thing I
align:start position:0%
plot as you can see here another thing I
align:start position:0%
plot as you can see here another thing I
would like to mention is look at the
align:start position:0%
would like to mention is look at the
align:start position:0%
would like to mention is look at the
proportionality here as we increase the
align:start position:0%
proportionality here as we increase the
align:start position:0%
proportionality here as we increase the
power we also increase the stiffness
align:start position:0%
power we also increase the stiffness
align:start position:0%
power we also increase the stiffness
coefficient alpha because we trap more
align:start position:0%
coefficient alpha because we trap more
align:start position:0%
coefficient alpha because we trap more
closely so it means that F nost has to
align:start position:0%
closely so it means that F nost has to
align:start position:0%
closely so it means that F nost has to
increase and indeed when we increase the
align:start position:0%
increase and indeed when we increase the
align:start position:0%
increase and indeed when we increase the
power we are shifting F naught to the
align:start position:0%
power we are shifting F naught to the
align:start position:0%
power we are shifting F naught to the
right having all these components
align:start position:0%
right having all these components
align:start position:0%
right having all these components
we can put this into the big picture and
align:start position:0%
we can put this into the big picture and
align:start position:0%
we can put this into the big picture and
the big picture is the extraction of KB
align:start position:0%
the big picture is the extraction of KB
align:start position:0%
the big picture is the extraction of KB
over here I showed you x squared the
align:start position:0%
over here I showed you x squared the
align:start position:0%
over here I showed you x squared the
fluctuations I showed you alpha we can
align:start position:0%
fluctuations I showed you alpha we can
align:start position:0%
fluctuations I showed you alpha we can
measure the temperature T and then we
align:start position:0%
measure the temperature T and then we
align:start position:0%
measure the temperature T and then we
can get Kb the essence of this
align:start position:0%
can get Kb the essence of this
align:start position:0%
can get Kb the essence of this
measurement is to look at the inverse
align:start position:0%
measurement is to look at the inverse
align:start position:0%
measurement is to look at the inverse
proportionality between fluctuations and
align:start position:0%
proportionality between fluctuations and
align:start position:0%
proportionality between fluctuations and
trap stiffness then we can make a fit
align:start position:0%
trap stiffness then we can make a fit
align:start position:0%
trap stiffness then we can make a fit
with a reasonable chi-square probability
align:start position:0%
with a reasonable chi-square probability
align:start position:0%
with a reasonable chi-square probability
and from here we can extract Kb the
align:start position:0%
and from here we can extract Kb the
align:start position:0%
and from here we can extract Kb the
result is presented on the slide we also
align:start position:0%
result is presented on the slide we also
align:start position:0%
result is presented on the slide we also
show you the measurement that we extract
align:start position:0%
show you the measurement that we extract
align:start position:0%
show you the measurement that we extract
from literature our result is within two
align:start position:0%
from literature our result is within two
align:start position:0%
from literature our result is within two
sigma of the accepted value of KB
align:start position:0%
sigma of the accepted value of KB
align:start position:0%
sigma of the accepted value of KB
actually we're very close to 1 Sigma
align:start position:0%
actually we're very close to 1 Sigma
align:start position:0%
actually we're very close to 1 Sigma
from the accepted value of KB what is
align:start position:0%
from the accepted value of KB what is
align:start position:0%
from the accepted value of KB what is
driving this like unfortunate outcome
align:start position:0%
driving this like unfortunate outcome
align:start position:0%
driving this like unfortunate outcome
the thing that drives this unfortunate
align:start position:0%
the thing that drives this unfortunate
align:start position:0%
the thing that drives this unfortunate
outcome is the systematic errors on our
align:start position:0%
outcome is the systematic errors on our
align:start position:0%
outcome is the systematic errors on our
picture this is our starting error this
align:start position:0%
picture this is our starting error this
align:start position:0%
picture this is our starting error this
is the uncertainty in KB and there are
align:start position:0%
is the uncertainty in KB and there are
align:start position:0%
is the uncertainty in KB and there are
different factors that contribute it to
align:start position:0%
different factors that contribute it to
align:start position:0%
different factors that contribute it to
this as you saw the calibration is very
align:start position:0%
this as you saw the calibration is very
align:start position:0%
this as you saw the calibration is very
difficult
align:start position:0%
difficult
align:start position:0%
difficult
we have error from the laser hitting the
align:start position:0%
we have error from the laser hitting the
align:start position:0%
we have error from the laser hitting the
water and changing the temperature we
align:start position:0%
water and changing the temperature we
align:start position:0%
water and changing the temperature we
have systematic error of the electronics
align:start position:0%
have systematic error of the electronics
align:start position:0%
have systematic error of the electronics
which we safely ignore because the first
align:start position:0%
which we safely ignore because the first
align:start position:0%
which we safely ignore because the first
two factors dominate this our
align:start position:0%
two factors dominate this our
align:start position:0%
two factors dominate this our
electronics were very precise and then
align:start position:0%
electronics were very precise and then
align:start position:0%
electronics were very precise and then
we have the statistical uncertainties
align:start position:0%
we have the statistical uncertainties
align:start position:0%
we have the statistical uncertainties
that we use which correspond to some
align:start position:0%
that we use which correspond to some
align:start position:0%
that we use which correspond to some
error propagating tricks okay now let's
align:start position:0%
error propagating tricks okay now let's
align:start position:0%
error propagating tricks okay now let's
do our investigation the first one is
align:start position:0%
do our investigation the first one is
align:start position:0%
do our investigation the first one is
about the calibration as you can see all
align:start position:0%
about the calibration as you can see all
align:start position:0%
about the calibration as you can see all
of these slopes should be valid but
align:start position:0%
of these slopes should be valid but
align:start position:0%
of these slopes should be valid but
they're actually not so what we do is we
align:start position:0%
they're actually not so what we do is we
align:start position:0%
they're actually not so what we do is we
take them into account we average them
align:start position:0%
take them into account we average them
align:start position:0%
take them into account we average them
then we take more data points we average
align:start position:0%
then we take more data points we average
align:start position:0%
then we take more data points we average
again and then we propagate the errors
align:start position:0%
again and then we propagate the errors
align:start position:0%
again and then we propagate the errors
in order to reduce the systematics the
align:start position:0%
in order to reduce the systematics the
align:start position:0%
in order to reduce the systematics the
second one is due to the heating of the
align:start position:0%
second one is due to the heating of the
align:start position:0%
second one is due to the heating of the
laser essentially what happens is when
align:start position:0%
laser essentially what happens is when
align:start position:0%
laser essentially what happens is when
the laser hits the water it starts
align:start position:0%
the laser hits the water it starts
align:start position:0%
the laser hits the water it starts
heating the vicinity and this is
align:start position:0%
heating the vicinity and this is
align:start position:0%
heating the vicinity and this is
unfortunate because yes we can measure
align:start position:0%
unfortunate because yes we can measure
align:start position:0%
unfortunate because yes we can measure
the room temperature by using the therm
align:start position:0%
the room temperature by using the therm
align:start position:0%
the room temperature by using the therm
but actual uncertainty on the
align:start position:0%
but actual uncertainty on the
align:start position:0%
but actual uncertainty on the
temperature is much bigger because we
align:start position:0%
temperature is much bigger because we
align:start position:0%
temperature is much bigger because we
have extra heating due to the laser we
align:start position:0%
have extra heating due to the laser we
align:start position:0%
have extra heating due to the laser we
tried elegantly to to avoid this by
align:start position:0%
tried elegantly to to avoid this by
align:start position:0%
tried elegantly to to avoid this by
moving the laser constantly so that it
align:start position:0%
moving the laser constantly so that it
align:start position:0%
moving the laser constantly so that it
doesn't stay in one place and heat up a
align:start position:0%
doesn't stay in one place and heat up a
align:start position:0%
doesn't stay in one place and heat up a
lot but it's very hard to quantify how
align:start position:0%
lot but it's very hard to quantify how
align:start position:0%
lot but it's very hard to quantify how
exactly it heats up the water and the
align:start position:0%
exactly it heats up the water and the
align:start position:0%
exactly it heats up the water and the
third one is it's concerned with our fit
align:start position:0%
third one is it's concerned with our fit
align:start position:0%
third one is it's concerned with our fit
with fluctuations in terms of the trap
align:start position:0%
with fluctuations in terms of the trap
align:start position:0%
with fluctuations in terms of the trap
stiffness initially when we did the fit
align:start position:0%
stiffness initially when we did the fit
align:start position:0%
stiffness initially when we did the fit
we with the PhD method we get a
align:start position:0%
we with the PhD method we get a
align:start position:0%
we with the PhD method we get a
probability of chi-square equals 0 and
align:start position:0%
probability of chi-square equals 0 and
align:start position:0%
probability of chi-square equals 0 and
then we quickly realize that essentially
align:start position:0%
then we quickly realize that essentially
align:start position:0%
then we quickly realize that essentially
what we need to do is take into account
align:start position:0%
what we need to do is take into account
align:start position:0%
what we need to do is take into account
the horizontal errors and here what we
align:start position:0%
the horizontal errors and here what we
align:start position:0%
the horizontal errors and here what we
do is we transform the horizontal errors
align:start position:0%
do is we transform the horizontal errors
align:start position:0%
do is we transform the horizontal errors
into the vertical errors and this thing
align:start position:0%
into the vertical errors and this thing
align:start position:0%
into the vertical errors and this thing
we can do by using adding addition in
align:start position:0%
we can do by using adding addition in
align:start position:0%
we can do by using adding addition in
quadrature and propagation of the errors
align:start position:0%
quadrature and propagation of the errors
align:start position:0%
quadrature and propagation of the errors
which gave us a reasonable realistic
align:start position:0%
which gave us a reasonable realistic
align:start position:0%
which gave us a reasonable realistic
chi-squared of 0.33 in conclusion I'll
align:start position:0%
chi-squared of 0.33 in conclusion I'll
align:start position:0%
chi-squared of 0.33 in conclusion I'll
start with limitations as you saw it's
align:start position:0%
start with limitations as you saw it's
align:start position:0%
start with limitations as you saw it's
very hard to distinguish between
align:start position:0%
very hard to distinguish between
align:start position:0%
very hard to distinguish between
systematic errors and statistical
align:start position:0%
systematic errors and statistical
align:start position:0%
systematic errors and statistical
uncertainties the reason for this is as
align:start position:0%
uncertainties the reason for this is as
align:start position:0%
uncertainties the reason for this is as
you saw is that we are fighting with the
align:start position:0%
you saw is that we are fighting with the
align:start position:0%
you saw is that we are fighting with the
systematics by introducing more
align:start position:0%
systematics by introducing more
align:start position:0%
systematics by introducing more
statistics and everything mixes up in
align:start position:0%
statistics and everything mixes up in
align:start position:0%
statistics and everything mixes up in
the propagation of errors the second
align:start position:0%
the propagation of errors the second
align:start position:0%
the propagation of errors the second
thing that it was very difficult in this
align:start position:0%
thing that it was very difficult in this
align:start position:0%
thing that it was very difficult in this
lab is that we need to move the laser
align:start position:0%
lab is that we need to move the laser
align:start position:0%
lab is that we need to move the laser
constantly so one of the one of the
align:start position:0%
constantly so one of the one of the
align:start position:0%
constantly so one of the one of the
people working on this topic has to keep
align:start position:0%
people working on this topic has to keep
align:start position:0%
people working on this topic has to keep
track of where the laser is and whether
align:start position:0%
track of where the laser is and whether
align:start position:0%
track of where the laser is and whether
you're trapping things that you may not
align:start position:0%
you're trapping things that you may not
align:start position:0%
you're trapping things that you may not
want to trap the third thing is to the
align:start position:0%
want to trap the third thing is to the
align:start position:0%
want to trap the third thing is to the
need to find better ways of calibration
align:start position:0%
need to find better ways of calibration
align:start position:0%
need to find better ways of calibration
and there are people who are actively
align:start position:0%
and there are people who are actively
align:start position:0%
and there are people who are actively
working on this on this topic here as
align:start position:0%
working on this on this topic here as
align:start position:0%
working on this on this topic here as
you saw the main source of error came
align:start position:0%
you saw the main source of error came
align:start position:0%
you saw the main source of error came
from the calibration actually but the
align:start position:0%
from the calibration actually but the
align:start position:0%
from the calibration actually but the
process is that we can give a reasonable
align:start position:0%
process is that we can give a reasonable
align:start position:0%
process is that we can give a reasonable
estimate to the Boltzmann constant and
align:start position:0%
estimate to the Boltzmann constant and
align:start position:0%
estimate to the Boltzmann constant and
at the same time we can have a lot of
align:start position:0%
at the same time we can have a lot of
align:start position:0%
at the same time we can have a lot of
fun while doing so I would like to thank
align:start position:0%
fun while doing so I would like to thank
align:start position:0%
fun while doing so I would like to thank
to my partner Emma and I think
align:start position:0%
to my partner Emma and I think
align:start position:0%
to my partner Emma and I think
collaboration is very important for
align:start position:0%
collaboration is very important for
align:start position:0%
collaboration is very important for
Jayla and more specifically for this
align:start position:0%
Jayla and more specifically for this
align:start position:0%
Jayla and more specifically for this
particular experiment this experiment is
align:start position:0%
particular experiment this experiment is
align:start position:0%
particular experiment this experiment is
impossible to be done without a partner
align:start position:0%
impossible to be done without a partner
align:start position:0%
impossible to be done without a partner
because it's very difficult it's very
align:start position:0%
because it's very difficult it's very
align:start position:0%
because it's very difficult it's very
difficult to keep track of where you
align:start position:0%
difficult to keep track of where you
align:start position:0%
difficult to keep track of where you
want to put
align:start position:0%
want to put
align:start position:0%
want to put
and also what is going on around the
align:start position:0%
and also what is going on around the
align:start position:0%
and also what is going on around the
laser well one of the people who is
align:start position:0%
laser well one of the people who is
align:start position:0%
laser well one of the people who is
moving the laser the other one should be
align:start position:0%
moving the laser the other one should be
align:start position:0%
moving the laser the other one should be
looking looking at the CCD camera and
align:start position:0%
looking looking at the CCD camera and
align:start position:0%
looking looking at the CCD camera and
like telling where are we going on like
align:start position:0%
like telling where are we going on like
align:start position:0%
like telling where are we going on like
what are we actually trapping like what
align:start position:0%
what are we actually trapping like what
align:start position:0%
what are we actually trapping like what
do we want to avoid like we don't want
align:start position:0%
do we want to avoid like we don't want
align:start position:0%
do we want to avoid like we don't want
these guys in our picture I also like to
align:start position:0%
these guys in our picture I also like to
align:start position:0%
these guys in our picture I also like to
thank the staff of this class for their
align:start position:0%
thank the staff of this class for their
align:start position:0%
thank the staff of this class for their
useful feedback and their valuable help
align:start position:0%
useful feedback and their valuable help
align:start position:0%
useful feedback and their valuable help
and finally for your attention yeah so
align:start position:0%
and finally for your attention yeah so
align:start position:0%
and finally for your attention yeah so
we have a lot of this should be trap
align:start position:0%
we have a lot of this should be trap
align:start position:0%
we have a lot of this should be trap
stiffness versus the this is the current
align:start position:0%
stiffness versus the this is the current
align:start position:0%
stiffness versus the this is the current
and here actually I haven't shown that
align:start position:0%
and here actually I haven't shown that
align:start position:0%
and here actually I haven't shown that
it's like the trap stiffness defers
align:start position:0%
it's like the trap stiffness defers
align:start position:0%
it's like the trap stiffness defers
whether you look in the X direction or
align:start position:0%
whether you look in the X direction or
align:start position:0%
whether you look in the X direction or
the Y direction the actual measurements
align:start position:0%
the Y direction the actual measurements
align:start position:0%
the Y direction the actual measurements
are analog is because the mathematics is
align:start position:0%
are analog is because the mathematics is
align:start position:0%
are analog is because the mathematics is
the same but as you can see here we have
align:start position:0%
the same but as you can see here we have
align:start position:0%
the same but as you can see here we have
different data points for the two cases
align:start position:0%
different data points for the two cases
align:start position:0%
different data points for the two cases
we account this into our considerations
align:start position:0%
we account this into our considerations
align:start position:0%
we account this into our considerations
yes yes
align:start position:0%
align:start position:0%
mmm
align:start position:0%
align:start position:0%
well I mean the air case well I mean
align:start position:0%
well I mean the air case well I mean
align:start position:0%
well I mean the air case well I mean
everything boils down to this this
align:start position:0%
everything boils down to this this
align:start position:0%
everything boils down to this this
consideration here okay let me just find
align:start position:0%
consideration here okay let me just find
align:start position:0%
consideration here okay let me just find
my explanation it boils down to the the
align:start position:0%
my explanation it boils down to the the
align:start position:0%
my explanation it boils down to the the
viscosity that dominates so in our case
align:start position:0%
viscosity that dominates so in our case
align:start position:0%
viscosity that dominates so in our case
we have the viscosity of water that
align:start position:0%
we have the viscosity of water that
align:start position:0%
we have the viscosity of water that
dominates when you look in different
align:start position:0%
dominates when you look in different
align:start position:0%
dominates when you look in different
mediums you might have different types
align:start position:0%
mediums you might have different types
align:start position:0%
mediums you might have different types
of viscosity which would change the
align:start position:0%
of viscosity which would change the
align:start position:0%
of viscosity which would change the
motions so I have the paper I I didn't
align:start position:0%
motions so I have the paper I I didn't
align:start position:0%
motions so I have the paper I I didn't
actually read through the whole details
align:start position:0%
actually read through the whole details
align:start position:0%
actually read through the whole details
of the how exactly the mathematics
align:start position:0%
of the how exactly the mathematics
align:start position:0%
of the how exactly the mathematics
changes probably does also probably and
align:start position:0%
changes probably does also probably and
align:start position:0%
changes probably does also probably and
other issues that are that may not arise
align:start position:0%
other issues that are that may not arise
align:start position:0%
other issues that are that may not arise
or may arise is the laser like in this
align:start position:0%
or may arise is the laser like in this
align:start position:0%
or may arise is the laser like in this
case like laser like heats up the the
align:start position:0%
case like laser like heats up the the
align:start position:0%
case like laser like heats up the the
water but I don't know how exactly the
align:start position:0%
water but I don't know how exactly the
align:start position:0%
water but I don't know how exactly the
laser would react with the air maybe
align:start position:0%
laser would react with the air maybe
align:start position:0%
laser would react with the air maybe
it's going to heat up a little bit but
align:start position:0%
it's going to heat up a little bit but
align:start position:0%
it's going to heat up a little bit but
how is this heat by going to be
align:start position:0%
how is this heat by going to be
align:start position:0%
how is this heat by going to be
distributed in space I'm not very
align:start position:0%
distributed in space I'm not very
align:start position:0%
distributed in space I'm not very
knowledgeable of this as it now
align:start position:0%
align:start position:0%
so the equipartition theorem it breaks
align:start position:0%
so the equipartition theorem it breaks
align:start position:0%
so the equipartition theorem it breaks
into components it breaks into the
align:start position:0%
into components it breaks into the
align:start position:0%
into components it breaks into the
component of X where we have one degree
align:start position:0%
component of X where we have one degree
align:start position:0%
component of X where we have one degree
of freedom and it breaks into the
align:start position:0%
of freedom and it breaks into the
align:start position:0%
of freedom and it breaks into the
component of Y where have another degree
align:start position:0%
component of Y where have another degree
align:start position:0%
component of Y where have another degree
of freedom
align:start position:0%
of freedom
align:start position:0%
of freedom
each of these considerations is
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each of these considerations is
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each of these considerations is
concerned only with in one movement so
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concerned only with in one movement so
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concerned only with in one movement so
for the okay well you can think about it
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for the okay well you can think about it
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for the okay well you can think about it
in this way we have two degrees of
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in this way we have two degrees of
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in this way we have two degrees of
freedom in total but in the actual
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freedom in total but in the actual
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freedom in total but in the actual
directions that are useful for our
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directions that are useful for our
align:start position:0%
directions that are useful for our
considerations we have only one degree
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considerations we have only one degree
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considerations we have only one degree
of freedom so yeah well I think this is
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of freedom so yeah well I think this is
align:start position:0%
of freedom so yeah well I think this is
for this this is 3.2 microns and this
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for this this is 3.2 microns and this
align:start position:0%
for this this is 3.2 microns and this
like later on like you might you saw the
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like later on like you might you saw the
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like later on like you might you saw the
1 microns
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1 microns
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1 microns
I think our data is concerned with the
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I think our data is concerned with the
align:start position:0%
I think our data is concerned with the
3.2 microns we didn't I like my results
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3.2 microns we didn't I like my results
align:start position:0%
3.2 microns we didn't I like my results
are not related with the micron 1 micron
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are not related with the micron 1 micron
align:start position:0%
are not related with the micron 1 micron
we just played with it and try this we
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we just played with it and try this we
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we just played with it and try this we
also tried the trapping cells from
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also tried the trapping cells from
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also tried the trapping cells from
onions it was very fun to play with but
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onions it was very fun to play with but
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onions it was very fun to play with but
unfortunately we couldn't get any like
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unfortunately we couldn't get any like
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unfortunately we couldn't get any like
valuable quantitative results there so
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valuable quantitative results there so
align:start position:0%
valuable quantitative results there so
even though it's quite a lot of fun we
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even though it's quite a lot of fun we
align:start position:0%
even though it's quite a lot of fun we
have some clips it's not worth for this
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have some clips it's not worth for this
align:start position:0%
have some clips it's not worth for this
presentation which concentrates on the
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presentation which concentrates on the
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presentation which concentrates on the
KB
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align:start position:0%
[Applause]