id stringlengths 9 16 | title stringlengths 4 278 | categories stringlengths 5 104 | abstract stringlengths 6 4.09k |
|---|---|---|---|
quant-ph/0605096 | Quantum Information and Entropy | quant-ph cs.IT math.IT | Thermodynamic entropy is not an entirely satisfactory measure of information
of a quantum state. This entropy for an unknown pure state is zero, although
repeated measurements on copies of such a pure state do communicate
information. In view of this, we propose a new measure for the informational
entropy of a quantu... |
quant-ph/0607111 | `Plausibilities of plausibilities': an approach through circumstances | quant-ph cs.AI | Probability-like parameters appearing in some statistical models, and their
prior distributions, are reinterpreted through the notion of `circumstance', a
term which stands for any piece of knowledge that is useful in assigning a
probability and that satisfies some additional logical properties. The idea,
which can b... |
quant-ph/0609117 | Quantum Pattern Retrieval by Qubit Networks with Hebb Interactions | quant-ph cond-mat.dis-nn cs.NE | Qubit networks with long-range interactions inspired by the Hebb rule can be
used as quantum associative memories. Starting from a uniform superposition,
the unitary evolution generated by these interactions drives the network
through a quantum phase transition at a critical computation time, after which
ferromagneti... |
quant-ph/0609229 | Ergodic Classical-Quantum Channels: Structure and Coding Theorems | quant-ph cs.IT math-ph math.IT math.MP | We consider ergodic causal classical-quantum channels (cq-channels) which
additionally have a decaying input memory. In the first part we develop some
structural properties of ergodic cq-channels and provide equivalent conditions
for ergodicity. In the second part we prove the coding theorem with weak
converse for ca... |
quant-ph/0610153 | Subsystem Codes | quant-ph cs.IT math.IT | We investigate various aspects of operator quantum error-correcting codes or,
as we prefer to call them, subsystem codes. We give various methods to derive
subsystem codes from classical codes. We give a proof for the existence of
subsystem codes using a counting argument similar to the quantum
Gilbert-Varshamov boun... |
quant-ph/0610200 | Quantum List Decoding of Classical Block Codes of Polynomially Small
Rate from Quantumly Corrupted Codewords | quant-ph cs.CC cs.IT math.IT | Given a classical error-correcting block code, the task of quantum list
decoding is to produce from any quantumly corrupted codeword a short list
containing all messages whose codewords exhibit high "presence" in the
quantumly corrupted codeword. Efficient quantum list decoders have been used to
prove a quantum hardc... |
quant-ph/0611167 | Continuous Variable Quantum Cryptography using Two-Way Quantum
Communication | quant-ph cs.CR cs.IT math.IT physics.optics | Quantum cryptography has been recently extended to continuous variable
systems, e.g., the bosonic modes of the electromagnetic field. In particular,
several cryptographic protocols have been proposed and experimentally
implemented using bosonic modes with Gaussian statistics. Such protocols have
shown the possibility... |
quant-ph/0612052 | Deciding whether a quantum state has secret correlations is an
NP-complete problem | quant-ph cs.IT math.IT | From the NP-hardness of the quantum separability problem and the relation
between bipartite entanglement and the secret key correlations, it is shown
that the problem deciding whether a given quantum state has secret correlations
in it or not is in NP-complete.
|
quant-ph/0612155 | A father protocol for quantum broadcast channels | quant-ph cs.IT math.IT | A new protocol for quantum broadcast channels based on the fully quantum
Slepian-Wolf protocol is presented. The protocol yields an achievable rate
region for entanglement-assisted transmission of quantum information through a
quantum broadcast channel that can be considered the quantum analogue of
Marton's region fo... |
quant-ph/0701020 | Quantum Quasi-Cyclic LDPC Codes | quant-ph cs.IT math-ph math.CO math.IT math.MP | In this paper, a construction of a pair of "regular" quasi-cyclic LDPC codes
as ingredient codes for a quantum error-correcting code is proposed. That is,
we find quantum regular LDPC codes with various weight distributions.
Furthermore our proposed codes have lots of variations for length, code rate.
These codes are... |
quant-ph/0701037 | Quantum Convolutional Codes Derived From Reed-Solomon and Reed-Muller
Codes | quant-ph cs.IT math.IT | Convolutional stabilizer codes promise to make quantum communication more
reliable with attractive online encoding and decoding algorithms. This paper
introduces a new approach to convolutional stabilizer codes based on direct
limit constructions. Two families of quantum convolutional codes are derived
from generaliz... |
quant-ph/0701168 | Using quantum key distribution for cryptographic purposes: a survey | quant-ph cs.CR cs.IT math.IT | The appealing feature of quantum key distribution (QKD), from a cryptographic
viewpoint, is the ability to prove the information-theoretic security (ITS) of
the established keys. As a key establishment primitive, QKD however does not
provide a standalone security service in its own: the secret keys established
by QKD... |
quant-ph/0702005 | A decoupling approach to the quantum capacity | quant-ph cs.IT math.IT | We give a short proof that the coherent information is an achievable rate for
the transmission of quantum information through a noisy quantum channel. Our
method is to produce random codes by performing a unitarily covariant
projective measurement on a typical subspace of a tensor power state. We show
that, provided ... |
quant-ph/0702072 | Markovian Entanglement Networks | quant-ph cs.AI | Graphical models of probabilistic dependencies have been extensively
investigated in the context of classical uncertainty. However, in some domains
(most notably, in computational physics and quantum computing) the nature of
the relevant uncertainty is non-classical, and the laws of classical
probability theory are s... |
quant-ph/0703112 | Graphs, Quadratic Forms, and Quantum Codes | quant-ph cs.IT math.IT | We show that any stabilizer code over a finite field is equivalent to a
graphical quantum code. Furthermore we prove that a graphical quantum code over
a finite field is a stabilizer code. The technique used in the proof
establishes a new connection between quantum codes and quadratic forms. We
provide some simple ex... |
quant-ph/0703113 | Quantum Convolutional BCH Codes | quant-ph cs.IT math.IT | Quantum convolutional codes can be used to protect a sequence of qubits of
arbitrary length against decoherence. We introduce two new families of quantum
convolutional codes. Our construction is based on an algebraic method which
allows to construct classical convolutional codes from block codes, in
particular BCH co... |
quant-ph/0703181 | Quantum Block and Convolutional Codes from Self-orthogonal Product Codes | quant-ph cs.IT math.IT | We present a construction of self-orthogonal codes using product codes. From
the resulting codes, one can construct both block quantum error-correcting
codes and quantum convolutional codes. We show that from the examples of
convolutional codes found, we can derive ordinary quantum error-correcting
codes using tail-b... |
quant-ph/0703182 | Constructions of Quantum Convolutional Codes | quant-ph cs.IT math.IT | We address the problems of constructing quantum convolutional codes (QCCs)
and of encoding them. The first construction is a CSS-type construction which
allows us to find QCCs of rate 2/4. The second construction yields a quantum
convolutional code by applying a product code construction to an arbitrary
classical con... |
quant-ph/9703022 | Reversibility and Adiabatic Computation: Trading Time and Space for
Energy | quant-ph cs.CC cs.CE cs.DS | Future miniaturization and mobilization of computing devices requires energy
parsimonious `adiabatic' computation. This is contingent on logical
reversibility of computation. An example is the idea of quantum computations
which are reversible except for the irreversible observation steps. We propose
to study quantita... |
quant-ph/9802028 | Analogue Quantum Computers for Data Analysis | quant-ph cs.CV | Analogue computers use continuous properties of physical system for modeling.
In the paper is described possibility of modeling by analogue quantum computers
for some model of data analysis. It is analogue associative memory and a formal
neural network. A particularity of the models is combination of continuous
inter... |
quant-ph/9809081 | Concatenating Decoherence Free Subspaces with Quantum Error Correcting
Codes | quant-ph cs.IT math-ph math.IT math.MP | An operator sum representation is derived for a decoherence-free subspace
(DFS) and used to (i) show that DFSs are the class of quantum error correcting
codes (QECCs) with fixed, unitary recovery operators, and (ii) find explicit
representations for the Kraus operators of collective decoherence. We
demonstrate how th... |
quant-ph/9907009 | The importance of quantum decoherence in brain processes | quant-ph cond-mat.dis-nn cs.NE physics.bio-ph q-bio | Based on a calculation of neural decoherence rates, we argue that that the
degrees of freedom of the human brain that relate to cognitive processes should
be thought of as a classical rather than quantum system, i.e., that there is
nothing fundamentally wrong with the current classical approach to neural
network simu... |
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