Quantum state transfer control based on the optimal measurement

Harraz, Sajede; Yang, Jerry Zhijian; Li, Kezhi; Cong, Shuang

doi:10.1002/oca.2287

Cited by 12 publications

(7 citation statements)

References 26 publications

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“…In classical definition, fisher information is measuring the amount of information that an observable random variable carries about an unknown parameter σ. The quantum fisher information is formally generalized from classical fisher information definition as [32,33]:…”

Section: Average Total Qfimentioning

confidence: 99%

Quantum fisher information protection of N-qubit Greenberger-Horne-Zeilinger state from decoherence

Harraz¹,

Cong²,

Zhang³

et al. 2021

Preprint

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In this paper we study the protection of N -qubit Greenberger-Horne-Zeilinger (GHZ) state and generalized N -qubit GHZ states in amplitude damping channel by means of quantum weak measurement and flip operations. We derive the explicit formulas of the performances of the protection scheme: average fidelity, average probability and the average quantum fisher information (QFI). Moreover, the analytical results for maximizing the average fidelity and probability are obtained. We show that our scheme can effectively protect the average QFI of phase for GHZ states and generalized GHZ states. The proposed scheme has the merit of protecting GHZ state and the QFI of phase against heavy amplitude damping noise. Further we show that for some generalize GHZ state, the proposed scheme can protect the state with probability one and fidelity more than 99%.

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Section: Average Total Qfimentioning

confidence: 99%

Quantum fisher information protection of N-qubit Greenberger-Horne-Zeilinger state from decoherence

Harraz¹,

Cong²,

Zhang³

et al. 2021

Preprint

Self Cite

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“…On the other hand, finding the best measurements is one of the significant challenges in quantum computing. Optimal measurements have been used in many context, such as quantum discrimination [2], quantum entanglement [3][4][5], quantum teleportation [6], and superdense coding [7], also in the calculation of quantum correlation [1,[8][9][10][11][12]. We know that quantum correlations play a very critical role in quantum information and computation.…”

Section: Introductionmentioning

confidence: 99%

Toward a quantum computing algorithm to quantify classical and quantum correlation of system states

Mahdian,

Yeganeh

2021

Preprint

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Optimal measurement is required to obtain the quantum and classical correlations of a quantum state, and the crucial difficulty is how to acquire the maximal information about one system by measuring the other part; in other words, getting the maximum information corresponds to preparing the best measurement operators. Within a general setup, we designed a variational hybrid quantum-classical (VHQC) algorithm to achieve classical and quantum correlations for system states under the Noisy-Intermediate Scale Quantum (NISQ) technology. To employ, first, we map the density matrix to the vector representation, which displays it in a doubled Hilbert space, and it's converted to a pure state. Then we apply the measurement operators to a part of the subsystem and use variational principle and a classical optimization for the determination of the amount of correlation. We numerically test the performance of our algorithm at finding a correlation of some density matrices, and the output of our algorithm is compatible with the exact calculation.

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“…For example, continuous weak measurement [8,9,10,11] and sequential unsharp measurement [12] with estimation methods such as maximum likelihood and Baysian method [13,14,15] have been widely used in experiments [16,17]. When the projective or strong measurements are acted, the state of the system will collapse to its eigenstates, thus one needs to reprepare the ensemble and measurement apparatus at each step [18]. The weak measurements offer a trade-off between information gain and the disturbance of the system [19].…”

Section: Introductionmentioning

confidence: 99%

Online quantum state tomography of N-qubit via continuous weak measurement and compressed sensing

Harraz

Cong

2020

Int. J. Quantum Inform.

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In this paper, we propose an online state tomography method for [Formula: see text]-qubit quantum system based on the continuous weak measurement and compressed sensing (CS). The quantum system is described by stochastic master equation. The continuous weak measurement operators for the [Formula: see text]-qubit quantum system, which are indirectly acted on the quantum system, are derived according to the measurement operator results of two-level quantum system. The online time-varying measurement operators are obtained by means of the dynamic evolution equation of the system. The quantum state is online estimated by solving the optimization problem of minimizing the two-norm with the positive definite constraints of density matrix, and we use the nonnegative least squares algorithm to solve the optimization problem. CS theory is used to reduce the number of the measurements in the process of online state estimation. In the numerical experiments, we study the effects of external control field, measurement rate and the different numbers of qubits on the performance in the proposed method. The minimum required numbers of measurements for 2, 3, 4 and 5 qubits are found. The normalized distance and fidelity of our proposed method can achieve satisfying accuracy with small number of measurements.

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Quantum state transfer control based on the optimal measurement

Cited by 12 publications

References 26 publications

Quantum fisher information protection of N-qubit Greenberger-Horne-Zeilinger state from decoherence

Quantum fisher information protection of N-qubit Greenberger-Horne-Zeilinger state from decoherence

Toward a quantum computing algorithm to quantify classical and quantum correlation of system states

Online quantum state tomography of N-qubit via continuous weak measurement and compressed sensing

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