Effects of partial measurements on quantum resources and quantum Fisher information of a teleported state in a relativistic scenario

Abstract

We address the teleportation of single- and two-qubit quantum states, parametrized by weight θ and phase ϕ parameters, in the presence of the Unruh effect experienced by a mode of a free Dirac field. We investigate the effects of the partial measurement (PM) and partial measurement reversal (PMR) on the quantum resources and quantum Fisher information (QFI) of the teleported states. In particular, we discuss the optimal behaviour of the QFI, quantum coherence (QC) as well as fidelity with respect to the PM and PMR strength and examine the effect of the Unruh noise on optimal estimation. It is found that, in the single-qubit scenario, the PM (PMR) strength at which the optimal estimation of the phase parameter occurs is the same as the PM (PMR) strength with which the teleportation fidelity and the QC of the teleported single-qubit state reaches its maximum value. On the other hand, generalizing the results to two-qubit teleportation, we find that the encoded information in the weight parameter is better protected against the Unruh noise in two-qubit teleportation than in the one-qubit scenario. However, extraction of information encoded in the phase parameter is more efficient in single-qubit teleportation than in the two-qubit version.

Monitoring variations of refractive index via Hilbert–Schmidt speed and applying this phenomenon to improve quantum metrology

“…The field of quantum metrology [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] has provided valuable tools, such as the classical Fisher information and the quantum Fisher information (QFI) [19][20][21][22][23][24][25][26][27], for estimating the sensitivity of measurement devices and unknown parameters. Such analyses are usually focused on finding optimal measurement strategies, with respect to environmental parameters as well as initial conditions, to achieve measurement sensitivities better than the standard quantum limit [28].…”

Estimating energy levels of a three-level atom in single and multi-parameter metrological schemes

“…Conversely, the technical one is mostly represented by the accidental error, because of out-ofcontrol imperfections in the measurement process. Since quantum mechanics is the most fundamental, predictive, and successful theory describing small scale phenomena, an investigation of the measurement process as well as the ultimate achievable precision bounds has to be done under the light of such theory [1][2][3][4][5][6][7][8]. In fact, on the one hand, quantum theory determines fundamental limits on the estimate precision.…”

Remote sensing and faithful quantum teleportation through non-localized qubits

“…High-precision parameter estimation is a fundamental task throughout science. Generally speaking, there are two different scenarios for quantum parameter estimation in the presence of noises [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. In both approaches, the most important goals is to investigate the optimized measurement strategy such that as much information as possible about some parameter is achieved.…”