arXiv subjects

Ming Zhang

Publications and source records attributed to Ming Zhang.

425 records · Page 24Linked to original sources

arXiv2013

A new scheme for probabilistic teleportation and its potential applications

We propose a novel scheme for probabilistic teleportation when the information of the partially entangled state is only available for the sender. This is in contrast with the fact that the receiver must know the non-maximally entangled state in previous typical schemes for the teleportation. Additionally, we illustrate two potential applications of the novel scheme to probabilistically teleport an unknown two-level quantum state from a sender to a receiver with the help of an assistant, who plays distinguishable roles under different communication conditions, and the applications indicate that our proposal could improve the security and enlarge the applied range of probabilistic teleportation.

quant-ph↗

arXiv2012

Open quantum system identification

Engineering quantum systems offers great opportunities both technologically and scientifically for communication, computation, and simulation. The construction and operation of large scale quantum information devices presents a grand challenge and a major issue is the effective control of coherent dynamics. This is often in the presence of decoherence which further complicates the task of determining the behaviour of the system. Here, we show how to determine open system Markovian dynamics of a quantum system with restricted initialisation and partial output state information.

quant-ph↗

arXiv2012

Trajectory-constrained optimal local time-continuous waveform controls for state transitions in $N$-level quantum systems

Based on a parametrization of pure quantum states we explicitly construct a sequence of (at most) $4N-5$ local time-continuous waveform controls to achieve a specified state transition for $N$-level quantum systems when sufficient controls of the Hamiltonian are available. The control magnitudes are further optimized in terms of a time-energy performance, which is a generalization of the time performance index. Trajectory-constrained optimal local time-continuous waveform controls, including both local sine-waveforms and $n^{\rm th}$-order-polynomial waveform controls are obtained in terms of time-energy performance. It is demonstrated that constrained optimal local $n^{\rm th}$-order-polynomial waveform controls approach constrained optimal bang-bang controls when $n\rightarrow\infty$.

quant-ph↗

arXiv2011

On the role of a priori knowledge in the optimization of quantum information processing

This paper explores the role of a priori knowledge in the optimization of quantum information processing by investigating optimum unambiguous discrimination problems for both the qubit and qutrit states. In general, a priori knowledge in optimum unambiguous discrimination problems can be classed into two types: a priori knowledge of discriminated states themselves and a priori probabilities of preparing the states. It is clarified that whether a priori probabilities of preparing discriminated states are available or not, what type of discriminators one should design just depends on what kind of the classical knowledge of discriminated states. This is in contrast to the observation that choosing the parameters of discriminators not only relies on the a priori knowledge of discriminated states, but also depends on a priori probabilities of preparing the states. Two types of a priori knowledge can be utilized to improve optimum performance but play the different roles in the optimization from the view point of decision theory.

quant-ph↗

arXiv2011

Manipulating quantum information on the controllable systems or subspaces

In this paper, we explore how to constructively manipulate qubits by rotating Bloch spheres. It is revealed that three-rotation and one-rotation Hamiltonian controls can be constructed to steer qubits when two tunable Hamiltonian controls are available. It is demonstrated in this research that local-wave function controls such as Bang-Bang, triangle-function and quadratic function controls can be utilized to manipulate quantum states on the Bloch sphere. A new kind of time-energy performance index is proposed to trade-off time and energy resource cost, in which control magnitudes are optimized in terms of this kind of performance. It is further exemplified that this idea can be generalized to manipulate encoded qubits on the controllable subspace.

quant-ph↗

arXiv2011

Bang-Bang Control Design for Quantum State Transfer based on Hyperspherical Coordinates and Optimal Time-energy Control

We present a constructive control scheme for solving quantum state engineering problems based on a parametrization of the state vector in terms of complex hyperspherical coordinates. Unlike many control schemes based on factorization of unitary operators the scheme gives explicit expressions for all the Euler angles in terms of the hyperspherical coordinates of the initial and final state. The factorization, when applicable, has added benefits that phase rotations can be combined and performed concurrently. The control procedure can be realized using a simple bang-bang or square-wave-function controls. Optimal time-energy control is considered to find the optimal control amplitudes. The extension of the scheme to implement unitary operators is also discussed.

quant-ph↗

arXiv2010

Effective Strategies for Identifying Model Parameters for Open Quantum Systems

The problem of identifiability of model parameters for open quantum systems is considered by investigating two-level dephasing systems. We discuss under which conditions full information about the Hamiltonian and dephasing parameters can be obtained. Using simulated experiments several different strategies for extracting model parameters from limited and noisy data are compared.

quant-ph↗

arXiv2009

A systematic study of the $π^-/π^+$ ratio in heavy-ion collisions with the same neutron/proton ratio but different masses

A systematic study of the $π^-/π^+$ ratio in heavy-ion collisions with the same neutron/proton ratio but different masses can help single out effects of the nuclear mean field on pion production. Based on simulations using the IBUU04 transport model, it is found that the $π^-$ / $π^+$ ratio in head-on collisions of $^{48}$Ca+$^{48}$Ca, $^{124}$Sn +$^{124}$Sn and $^{197}$Au+$^{197}$Au at beam energies from 0.25 to 0.6 \agev increases with increasing the system size or decreasing the beam energies. A comprehensive analysis of the dynamical isospin fractionation and the \rpi ratio as well as their time evolution and spatial distributions demonstrates clearly that the \rpi ratio is an effective probe of the high-density behavior of the nuclear symmetry energy.

nucl-th↗

arXiv2009

Constraining the EOS of neutron-rich nuclear matter and properties of neutron stars with heavy-ion reactions

Heavy-ion reactions especially those induced by radioactive beams provide useful information about the density dependence of the nuclear symmetry energy, thus the Equation of State of neutron-rich nuclear matter, relevant for many astrophysical studies. The latest developments in constraining the symmetry energy at both sub- and supra-saturation densities from analyses of the isopsin diffusion and the $π^-/π^+$ ratio in heavy-ion collisions using the IBUU04 transport model are discussed. Astrophysical ramifications of the partially constrained symmetry energy on properties of neutron star crusts, gravitational waves emitted by deformed pulsars and the w-mode oscillations of neutron stars are presented briefly.

nucl-th↗

arXiv2009

Circumstantial evidence for a soft nuclear symmetry energy at supra-saturation densities

Within an isospin- and momentum-dependent hadronic transport model it is shown that the recent FOPI data on the $π^-/π^+$ ratio in central heavy-ion collisions at SIS/GSI energies (Willy Reisdorf {\it et al.}, NPA {\bf 781}, 459 (2007)) provide circumstantial evidence suggesting a rather soft nuclear symmetry energy \esym at $ρ\geq 2ρ_0$ compared to the Akmal-Pandharipande-Ravenhall prediction. Some astrophysical implications and the need for further experimental confirmations are discussed.

nucl-th↗

arXiv2006

Multivariate Lagrange Interpolation and an Application of Cayley-Bacharach Theorem For it

In this paper,we deeply research Lagrange interpolation of n-variables and give an application of Cayley-Bacharach theorem for it. We pose the concept of sufficient intersection about s algebraic hypersurfaces in n-dimensional complex Euclidean space and discuss the Lagrange interpolation along the algebraic manifold of sufficient intersection. By means of some theorems (such as Bezout theorem, Macaulay theorem and so on) we prove the dimension for the polynomial space P(n) m along the algebraic manifold S of sufficient intersection and give a convenient expression for dimension calculation by using the backward difference operator. According to Mysovskikh theorem, we give a proof of the existence and a characterizing condition of properly posed set of nodes of arbitrary degree for interpolation along an algebraic manifold of sufficient intersection. Further we point out that for s algebraic hypersurfaces of sufficient intersection, the set of polynomials must constitute the H-base of ideal. As a main result of this paper, we deduce a general method of constructing properly posed set of nodes for Lagrange interpolation along an algebraic manifold, namely the superposition interpolation process. At the end of the paper, we use the extended Cayley-Bacharach theorem to resolve some problems of Lagrange interpolation along the 0-dimensional and 1-dimensional algebraic manifold. Just the application of Cayley-Bacharach theorem constitutes the start point of constructing properly posed set of nodes along the high dimensional algebraic manifold by using the superposition interpolation process.

math.NA↗