We propose a physically reversible quantum measurement of an arbitrary spin- $s$ system using a spin- $j$ probe via an Ising interaction. In the case of a spin- $1∕2$ system $(s=1∕2)$ , we explicitly construct a reversing measurement and evaluate the degree of reversibility in terms of fidelity. The recovery of the measured state is pronounced when the probe has a high spin $(j>1∕2)$ , because the fidelity changes drastically during the reversible measurement and the reversing measurement. We also show that the reversing measurement scheme for a spin- $1∕2$ system can serve as an experimentally feasible approximate reversing measurement for a high-spin system $(s>1∕2)$ . If the interaction is sufficiently weak, the reversing measurement can recover a cat state almost deterministically in spite of there being a large fidelity change.We propose a physically reversible quantum measurement of an arbitrary spin-$s$ system using a spin-$j$ probe via an Ising interaction. In the case of a spin-$1∕2$ system $(s=1∕2)$, we explicitly construct a reversing measurement and evaluate the degree of reversibility in terms of fidelity. The recovery of the measured state is pronounced when the probe has a high spin $(j>1∕2)$, because the fidelity changes drastically during the reversible measurement and the reversing measurement. We also show that the reversing measurement scheme for a spin-$1∕2$ system can serve as an experimentally feasible approximate reversing measurement for a high-spin system $(s>1∕2)$. If the interaction is sufficiently weak, the reversing measurement can recover a cat state almost deterministically in spite of there being a large fidelity change.

arXiv:quant-ph/0507020Physical Review AJul 17, 200611 citations

On a one-dimensional spin system

Stanislav Alekseevich Molchanov, Nguyen The Long

Theoretical and Mathematical PhysicsOct 1, 19750 citations

Spin Measurements

Cosimo Bambi

Springer eBooksJan 1, 20220 citations

Measurements, quantum discord, and parity in spin-1 systems

R. Rossignoli, J. M. Matera, N. Canosa

We consider the evaluation of the quantum discord and other related measures of quantum correlations in a system formed by a spin-1 and a complementary spin system. A characterization of general projective measurements in such system in terms of spin averages is thereby introduced, which allows one to easily visualize their deviation from standard spin measurements. It is shown that the measurement optimizing these measures corresponds in general to a nonspin measurement. The important case of states that commute with the total ${S}_{z}$ spin-parity is discussed in detail, and the general stationary measurements for such states (parity preserving measurements) are identified. Numerical and analytical results for the quantum discord, the geometric discord, and the one way information deficit in the relevant case of a mixture of two aligned spin-1 states are also presented.We consider the evaluation of the quantum discord and other related measures of quantum correlations in a system formed by a spin-1 and a complementary spin system. A characterization of general projective measurements in such system in terms of spin averages is thereby introduced, which allows one to easily visualize their deviation from standard spin measurements. It is shown that the measurement optimizing these measures corresponds in general to a nonspin measurement. The important case of states that commute with the total ${S}_{z}$ spin-parity is discussed in detail, and the general stationary measurements for such states (parity preserving measurements) are identified. Numerical and analytical results for the quantum discord, the geometric discord, and the one way information deficit in the relevant case of a mixture of two aligned spin-1 states are also presented.

arXiv:1206.2971Physical Review AAug 3, 201222 citations

Spin Measurement in Quantum Electro-Mechanical Systems

Dian Wahyu Utami, Jason Twamley, Hsi‐Sheng Goan +1 more

Bulletin of the American Physical SocietyMar 7, 20070 citations

Quantum-state tomography for spin- l systems

Holger Friedrich Hofmann, Shigeki Takeuchi

We show that the density matrix of a spin- $l$ system can be described entirely in terms of the measurement statistics of projective spin measurements along a minimum of $4l+1$ different spin directions. It is thus possible to represent the complete quantum statistics of any $N$ -level system within the spherically symmetric three-dimensional space defined by the spin vector. An explicit method for reconstructing the density matrix of a spin-1 system from the measurement statistics of five nonorthogonal spin directions is presented and the generalization to spin- $l$ systems is discussed.We show that the density matrix of a spin-$l$ system can be described entirely in terms of the measurement statistics of projective spin measurements along a minimum of $4l+1$ different spin directions. It is thus possible to represent the complete quantum statistics of any $N$-level system within the spherically symmetric three-dimensional space defined by the spin vector. An explicit method for reconstructing the density matrix of a spin-1 system from the measurement statistics of five nonorthogonal spin directions is presented and the generalization to spin-$l$ systems is discussed.

arXiv:quant-ph/0310003Physical Review AApr 23, 200436 citations

We propose a physically reversible quantum measurement of an arbitrary spin-

s

system using a spin-

j

probe via an Ising interaction. In the case of a spin-

1∕2

system

(s=1∕2)

, we explicitly construct a reversing measurement and evaluate the degree of reversibility in terms of fidelity. The recovery of the measured state is pronounced when the probe has a high spin

(j>1∕2)

, because the fidelity changes drastically during the reversible measurement and the reversing measurement. We also show that the reversing measurement scheme for a spin-

1∕2

system can serve as an experimentally feasible approximate reversing measurement for a high-spin system

(s>1∕2)

. If the interaction is sufficiently weak, the reversing measurement can recover a cat state almost deterministically in spite of there being a large fidelity change.

{S}_{z}

spin-parity is discussed in detail, and the general stationary measurements for such states (parity preserving measurements) are identified. Numerical and analytical results for the quantum discord, the geometric discord, and the one way information deficit in the relevant case of a mixture of two aligned spin-1 states are also presented.

We show that the density matrix of a spin-

l

system can be described entirely in terms of the measurement statistics of projective spin measurements along a minimum of

4l+1

different spin directions. It is thus possible to represent the complete quantum statistics of any

N

-level system within the spherically symmetric three-dimensional space defined by the spin vector. An explicit method for reconstructing the density matrix of a spin-1 system from the measurement statistics of five nonorthogonal spin directions is presented and the generalization to spin-

l

systems is discussed.