Achieving the Holevo capacity of a pure state classical-quantum channel via unambiguous state discrimination

We investigate the discrimination of pure-mixed (quantum filtering) and mixed-mixed states and compare their optimal success probability with the one for discriminating other pairs of pure states superposed by the vectors included in the mixed states. We prove that under the equal-fidelity condition, the pure-pure state discrimination scheme is superior to the pure-mixed (mixed-mixed) one. With respect to quantum filtering, the coherence exists only in one pure state and is detrimental to the state discrimination for lower dimensional systems; while it is the opposite for the mixed-mixed case with symmetrically distributed coherence. Making an extension to infinite-dimensional systems, we find that the coherence which is detrimental to state discrimination may become helpful and vice versa.

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Classical-Quantum Channel Coding

Introduction to Quantum Information Science - Graduate Texts in Physics ◽

10.1007/978-3-662-43502-1_8 ◽

2014 ◽

pp. 205-229

Author(s):

Masahito Hayashi ◽

Satoshi Ishizaka ◽

Akinori Kawachi ◽

Gen Kimura ◽

Tomohiro Ogawa

Keyword(s):

Channel Coding ◽

Quantum Channel ◽

Classical Quantum

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Unambiguous State Discrimination in Quantum Key Distribution Based on Time Coding

Journal of Applied Spectroscopy ◽

10.1007/s10812-019-00897-z ◽

2019 ◽

Vol 86 (5) ◽

pp. 806-809 ◽

Cited By ~ 1

Author(s):

M. M. Eskandari ◽

D. B. Horoshko ◽

S. Ya. Kilin

Keyword(s):

Quantum Key Distribution ◽

Key Distribution ◽

State Discrimination ◽

Time Coding ◽

Unambiguous State Discrimination

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Heralded orthogonalisation of coherent states and their conversion to discrete-variable superpositions

Quantum Measurements and Quantum Metrology ◽

10.1515/qmetro-2017-0005 ◽

2017 ◽

Vol 4 (1) ◽

pp. 35-43 ◽

Cited By ~ 1

Author(s):

Regina Kruse ◽

Christine Silberhorn ◽

Tim Bartley

Keyword(s):

Information Processing ◽

Quantum Information ◽

Coherent States ◽

Quantum Information Processing ◽

Fundamental Property ◽

Discrete Variable ◽

Successful Operation ◽

State Discrimination ◽

Unambiguous State Discrimination

Abstract The nonorthogonality of coherent states is a fundamental property which prevents them from being perfectly and deterministically discriminated. Here, we present an experimentally feasible protocol for the probabilistic orthogonalisation of a pair of coherent states, independent of their amplitude and phase. In contrast to unambiguous state discrimination, a successful operation of our protocol is heralded without measuring the states. As such, they remain suitable for further manipulation and the obtained orthogonal states serve as a discretevariable basis. Therefore, our protocol doubles as a simple continuous-to-discrete variable converter, which may find application in hybrid continuous-discrete quantum information processing protocols.

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On Quantum Capacity and its Bound

Infinite Dimensional Analysis Quantum Probability and Related Topics ◽

10.1142/s0219025703001171 ◽

2003 ◽

Vol 06 (02) ◽

pp. 301-310 ◽

Cited By ~ 8

Author(s):

Masanori Ohya ◽

Igor V. Volovich

Keyword(s):

Quantum Channel ◽

Quantum Mechanical ◽

Quantum Capacity ◽

Classical Quantum ◽

Mutual Entropy

The quantum capacity of a pure quantum channel and that of classical-quantum-classical channel are discussed in detail based on the fully quantum mechanical mutual entropy. It is proved that the quantum capacity generalizes the so-called Holevo bound.

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