Transfer from Arbitrary Pure State to Target Mixed State for Quantum Systems

2011 ◽  
Vol 44 (1) ◽  
pp. 4638-4643
Author(s):  
J. WEN ◽  
S. CONG
Keyword(s):  
Mixed State ◽  
Pure State ◽  
Quantum Systems

Probabilistic secret sharing through noise quantum channe

2012 ◽  
Vol 12 (3&4) ◽  
pp. 253-261
Author(s):  
Satyabrata Adhikari ◽  
Indranil Chakrabarty ◽  
Pankaj Agrawal
Keyword(s):  
Quantum Information ◽  
Secret Sharing ◽  
Mixed State ◽  
Pure State ◽  
Noisy Channel ◽  
Noisy Channels ◽  
Superdense Coding ◽  
Classical Information ◽  
Phase Damping ◽  
Realistic Situation

In a realistic situation, the secret sharing of classical or quantum information will involve the transmission of this information through noisy channels. We consider a three qubit pure state. This state becomes a mixed-state when the qubits are distributed over noisy channels. We focus on a specific noisy channel, the phase-damping channel. We propose a protocol for secret sharing of classical information with this and related noisy channels. This protocol can also be thought of as cooperative superdense coding. We also discuss other noisy channels to examine the possibility of secret sharing of classical information.

MIXED-STATE ENTANGLEMENT IN THE LIGHT OF PURE-STATE ENTANGLEMENT CONSTRAINED BY SUPERSELECTION RULES

2005 ◽  
Author(s):  
STEPHEN D. BARTLETT ◽  
HOWARD. M. WISEMAN ◽  
ROBERT W. SPEKKENS ◽  
ANDREW C. DOHERTY
Keyword(s):  
Mixed State ◽  
Pure State

scholarly journals THE CHSH-TYPE INEQUALITIES FOR INFINITE-DIMENSIONAL QUANTUM SYSTEMS

2013 ◽  
Vol 27 (21) ◽  
pp. 1350151
Author(s):  
YU GUO
Keyword(s):  
Pure State ◽  
Bell Inequalities ◽  
Quantum Systems ◽  
Necessary Condition ◽  
Infinite Dimensional ◽  
Infinite Dimensional Systems ◽  
Pure States ◽  
Sufficient And Necessary Condition

By establishing CHSH operators and CHSH-type inequalities, we show that any entangled pure state in infinite-dimensional systems is entangled in a 2⊗2 subspace. We find that, for infinite-dimensional systems, the corresponding properties are similar to that of the two-qubit case: (i) The CHSH-type inequalities provide a sufficient and necessary condition for separability of pure states; (ii) The CHSH operators satisfy the Cirel'son inequalities; (iii) Any state which violates one of these Bell inequalities is distillable.

Quantum Dynamics and Entropy in a Single-Cooper-Pair Box with a Single-Mode Cavity Field

2003 ◽  
Vol 17 (14) ◽  
pp. 2699-2713 ◽  
Author(s):  
Meng Zhang ◽  
Jian Zou ◽  
Bin Shao
Keyword(s):  
Mixed State ◽  
Pure State ◽  
Quantum Dynamics ◽  
Cooper Pair ◽  
Single Mode ◽  
Quantum Entropy ◽  
Cavity Field ◽  
Cooper Pair Box ◽  
Quantized Field ◽  
Single Mode Cavity

We consider a single-Cooper-pair box biased by a classical voltage and also irradiated by a single-mode quantized field. We assume that the box is initially in a mixed state, and investigate the quantum dynamics of the Cooper-pair box and show that the collapse and revival phenomenon can exist in this system. We also study the quantum entropy of the single-Cooper-pair box and discuss the effects of the different parameters on this quantum entropy. We find that the box, which is initially in a mixed state, may evolve into an almost pure state.

scholarly journals SOME FEATURES OF THE STATE-SPACE TRAJECTORIES FOLLOWED BY ROBUST ENTANGLED FOUR-QUBIT STATES DURING DECOHERENCE

2010 ◽  
Vol 08 (03) ◽  
pp. 505-515 ◽  
Author(s):  
A. P. MAJTEY ◽  
A. BORRAS ◽  
A. R. PLASTINO ◽  
M. CASAS ◽  
A. PLASTINO
Keyword(s):  
State Space ◽  
Recent Work ◽  
Mixed State ◽  
Pure State ◽  
The State ◽  
Time Dependent ◽  
Space Trajectories ◽  
Geometrical Features ◽  
Initial States ◽  
Qubit States

In a recent work (Borras et al., Phys. Rev. A79 (2009) 022108), we have determined, for various decoherence channels, four-qubit initial states exhibiting the most robust possible entanglement. Here, we explore some geometrical features of the trajectories in state space generated by the decoherence process, connecting the initially robust pure state with the completely decohered mixed state obtained at the end of the evolution. We characterize these trajectories by recourse to the distance between the concomitant time-dependent mixed state and different reference states.

scholarly journals Efficient algorithm for optimal control of mixed-state quantum systems

1999 ◽  
Vol 61 (1) ◽  
Author(s):  
S. G. Schirmer ◽  
M. D. Girardeau ◽  
J. V. Leahy
Keyword(s):  
Optimal Control ◽  
Mixed State ◽  
Efficient Algorithm ◽  
Quantum Systems

scholarly journals New Equilibrium Ensembles for Isolated Quantum Systems

Entropy ◽  
2018 ◽  
Vol 20 (10) ◽  
pp. 744 ◽  
Author(s):  
Fabio Anza
Keyword(s):  
Quantum System ◽  
Maximum Entropy ◽  
Pure State ◽  
Maximum Entropy Principle ◽  
Quantum Systems ◽  
Novel Technique ◽  
Entropy Principle ◽  
Do So

The unitary dynamics of isolated quantum systems does not allow a pure state to thermalize. Because of that, if an isolated quantum system equilibrates, it will do so to the predictions of the so-called “diagonal ensemble” ρ DE . Building on the intuition provided by Jaynes’ maximum entropy principle, in this paper we present a novel technique to generate progressively better approximations to ρ DE . As an example, we write down a hierarchical set of ensembles which can be used to describe the equilibrium physics of small isolated quantum systems, going beyond the “thermal ansatz” of Gibbs ensembles.

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