Quantum state discrimination of coherent states has been one important problems in quantum information processing. Recently, R. Han et al. showed that minimum error two can be nearly done by using Jaynes-Cummings Hamiltonian. In this paper, based on the result al., we propose methods where more than weak performed. Specially, construct models which do almost three and four states. Our applied to processing various

Recently, J. A. Bergou et al. proposed sequential state discrimination as a new quantum scheme. In the scheme, by successful of qubit state, receivers Bob and Charlie can share information prepared sender Alice. A merit scheme is that channel established between Charlie, but classical communication not allowed. this report, we present method for extending original two states to N linearly independent pure states. Specifically, obtain conditions = 3 We analytically provide when there special...

Sequential state discrimination is a strategy for quantum of sender's states when N receivers are separately located. In this report, we propose optical designs that can perform sequential two coherent states. For purpose, consider not only binary phase-shifting-key (BPSK) signals but also general states, with arbitrary prior probabilities. Since our do include electric feedback, they be implemented without difficulty. Furthermore, analyze proposal the case photon loss. We demonstrate...

Recently, sequential state discrimination, as a quantum-key distribution protocol, has been proposed for multiple receivers. A previous study [J. A. Bergou et al., Phys. Rev. Lett. 111, 100501 (2013)] showed that every receiver could successfully perform discrimination of two pure states with identical prior probabilities. In this study, we extend the to mixed arbitrary probability. First, analytically obtain condition receiver's optimal measurement. addition, show probability share prepared...

Abstract Multi-mode NOON states can quantum-enhance multiple-phase estimation in the absence of photon loss. However, a multi-mode state is known to be vulnerable loss, and its quantum-enhancement dissipated by lossy environment. In this work, we demonstrate that quantum advantage estimate precision still achieved presence This accomplished optimizing weights according loss rates multiple modes, including reference mode which defines other phases. For practical relevance, also show...

Abstract Sequential state discrimination is a strategy for N separated receivers. As sequential can be applied to multiparty quantum key distribution (QKD), it has become one of the relevant research fields in information theory. Up now, analysis been confined special cases. In this report, we consider generalization discrimination. Here, do not limit prior probabilities and number states We show that generalized expressed as an optimization problem. Moreover, investigate structure two apply...

Unambiguous quantum state discrimination is a strategy where the conclusive result can always be trusted. This very important, since it used for various information protocols, including key distribution. However, in view of quantumness, not clear what going on performing unambiguous discrimination. To answer question, we investigate coherence distribution when performed by generalized measurement. Specially, study three cases, which consist discrimination, sequential and assisted optimal are...

Multi-mode NOON states can quantum-enhance multiple-phase estimation in the absence of photon loss. However, a multi-mode state is known to be vulnerable loss, and its quantum-enhancement dissipated by lossy environment. In this work, we demonstrate that quantum advantage estimate precision still achieved presence This accomplished optimizing weights according loss rates multiple modes, including reference mode which defines other phases. For practical relevance, also show photon-number...

In quantum computation, what contributes supremacy of computation? One the candidates is known to be a coherence because it resource used in various algorithms. We reveal that training variational perceptron proposed by Y. Du et al., arXiv:1809.06056 (2018). detail, we show first part perceptron, total system concentrated index register and second part, Grover algorithm consumes register. This implies distribution depletion are required perceptron. addition, investigate behavior entanglement...

In this article, we investigate the error bound of quantum discord, obtained by analytic formula Ali et al.[Phys. Rev. A 81(2010), 042105] in case general X states and Fanchini 052107] symmetric states. We show that results et. al. to may have worst-case 0.004565 0.0009 respectively.

Abstract The quantum key distribution for multiparty is one of the essential subjects study. Especially, without using entangled states, performing a critical area research. For this purpose, sequential state discrimination, which provides communication and multiple receivers, has recently been introduced. Moreover, discrimination applicable security analysis against an eavesdropper’s attack. In work, we provide by proposing unified model including eavesdropper. model, success probability...

It is well known that the Helstrom bound can be improved by generalizing form of a coherent state. Thus, designing quantum measurement achieving important for novel communication. In this paper, we analytically show achieved projective composed orthogonal non-standard Schrödinger cat states. Moreover, numerically nearly an indirect based on Jaynes–Cummings model. As model describes interaction between light and two-level atom, emphasize considered in paper has potential to experimentally implemented.

For a multipartite quantum state, the maximal violation of all Bell inequalities constitutes measure its nonlocality [Loubenets, J. Math. Phys. 53, 022201 (2012)]. In present article, for by pure bipartite possibly infinite-dimensional, we derive new upper bound expressed in terms Schmidt coefficients this state. This allows us also to specify general analytical relations between or mixed, and such entanglement measures state as "negativity" "concurrence". To our knowledge, no any have been...

A general scenario for an $N$-sequential conclusive state discrimination introduced recently in Loubenets and Namkung [arXiv:2102.04747] can provide a multipartite quantum communication realizable the presence of noise. In present article, we propose new experimental scheme implementation sequential between binary coherent states via indirect measurements within Jaynes-Cummings interaction model. We find that if mean photon number is less than 1.6, then, our two-sequential scheme, optimal...

In this article we investigate the non-classical correlation in a macroscopic physical system. As tool, consider an optical hybrid state that is micro–macro entangled state. Our strategy to study behavior of may go through noisy channels. We violation two inequalities, which are CHSH-inequality and (generalized) CHSH-like-inequality, as measures correlation. First, find when on/off or parity measurements used for side coherent state, same CHSH-like-inequality. Second, see each measurement...

In this study, we model the dissipative dynamics of a charge qubit–atom hybrid under Born–Markov limit. Especially, focus on physical relation between spectral density and dynamics. Analytically, show that, if in is nearly linear function, then relaxation dephasing noises separately affect gate capacitor Josephson junction, respectively, but genuine-nonlinear these two both junction. Further, observe that numerical way, when there are some cases which corresponding environment dramatically...

A squeezed-displaced state can be used as an optical signal for efficient binary quantum communication. Here, we consider communication where atomic indirect measurement is to decide the message encoded in a phase-shift-keying composed of states, and show that incorrect decision probability less than homodyne measurement. We further lower even when channel exposed weak phase-diffusion noise.

The quantum key distribution for multiparty is one of the essential subjects study. Especially, without using entangled states, performing a critical area research. For this purpose, sequential discrimination, which provides communication and {multiple receivers}, has recently been introduced. However, since there possibility eavesdropping on measurement result receiver by an intruder entanglement, security analysis {quantum distribution} should be performed. {However,} no provided in view...

It is well known that the maximal success probability of binary quantum communication can be improved by using a sub-Poissonian non-standard coherent state as an information carrier. In present article, we consider with $N$-ary phase shift keying ($N$-PSK) signal for arbitrary positive integer $N>1$. By state, analytically provide $N$-PSK. Unlike case, show even super-Poissonianity improve $N$-PSK communication.

In the present article, based on formalism introduced in [Loubenets, J. Math. Phys. 53, 022201 (2012)], we derive for a pure bipartite quantum state new upper bound its maximal violation of general Bell inequalities. This indicates that, an infinite dimensional with finite sum Schmidt coefficients, any inequality is bounded from above by value independent number settings and type outcomes, continuous or discrete, specific to this inequality. As example, apply our results specifying bounds...