arXiv subjects

Yawen Tang

Publications and source records attributed to Yawen Tang.

3 recordsLinked to original sources

arXiv2026

Simultaneous estimation of relative phase and coherence in astronomical interferometry

Astronomical interferometry is a cornerstone technique for high-resolution stellar imaging and observational astrophysics, extracting spatial information from the coherence of light collected by separated telescopes. Since the degree of coherence is complex, a genuine imaging task requires the joint recovery of the modulus and the relative phase, instead of independent singleparameter estimations. We investigate the simultaneous estimation of both parameters based on direct interferometry scheme and continuou-svariable quantum teleportation scheme. We find that in simultaneous estimation the direct interferometry scheme consistently yields a lower quantum Cram\'er-Rao bound, demonstrating its superiority over the continuous-variable quantum teleportation scheme. Furthermore, we establish the conditions under which the classical Cram\'er-Rao bound for Gaussian measurements saturates the quantum Cram\'er-Rao bound, identifying heterodyne detection as a near-optimal measurement scheme in the large mean photon number regime. An analysis of transmission loss reveals that the direct interferometry scheme yields superior precision in the short-baseline regime, whereas the continuous-variable quantum teleportation scheme outperforms it at longer baselines.

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arXiv2026

Impact of the Unruh effect on the estimation precision of Gaussian channel parameters

Gaussian quantum channels constitute a pivotal physical framework for characterizing the dynamics of Gaussian quantum states. Extensive scholarly attention has been devoted to the estimation of parameters associated with Gaussian channels. However, while previous research has predominantly focused on parameter estimation within inertial frames, the noninertial scenario, particularly in the context of the Unruh effect, remains largely unexplored. In this paper, we analyze the impact of the Unruh effect on the estimation precision of Gaussian channel parameters, with a specific focus on thermal attenuator and thermal amplifier channels. Our findings reveal that the Unruh effect significantly degrades the precision of single-parameter estimation for Gaussian channel parameters when employing both the input coherent state and squeezed vacuum state. For the two-parameter estimation, we further demonstrate that the quantum Cram\'er-Rao bound serves as an asymptotically achievable precision limit. Consistent with the single-parameter case, the Unruh effect exerts a detrimental impact on the precision of two-parameter estimation. Notably, heterodyne measurement is near-optimal for both single- and two-parameter estimation in the limit of high acceleration or large thermal mean numbers. These results provide crucial theoretical insights and practical guidance for advancing quantum parameter estimation in a relativistic context.

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arXiv2026

Multiparameter quantum estimation with a uniformly accelerated Unruh-DeWitt detector

The uniformly accelerated Unruh-DeWitt detector serves as a fundamental model in relativistic quantum metrology. While previous studies have mainly concentrated on single-parameter estimation via quantum Cram\'er-Rao bound, the multi-parameter case remains significantly underexplored. In this paper, we investigate the multiparameter estimation for a uniformly accelerated Unruh-DeWitt detector coupled to a vacuum scalar field in both bounded and unbounded Minkowski vacuum. Our analysis reveals that quantum Cram\'er-Rao bound fails to provide a tight error bound for the two-parameter estimation involving the initial phase and weight parameters. For this reason, we numerically compute two tighter error bounds, Holevo Cram\'er-Rao bound and Nagaoka bound, based on a semidefinite program. Notably, our results demonstrate that Nagaoka bound yields the tightest error bound among all the considered error bounds, consistent with the general hierarchy of multiparameter quantum estimation. In the case with a boundary, we observe the introduction of boundary systematically reduces the values of both Holevo Cram\'er-Rao bound and Nagaoka bound, indicating an improvement on the attainable estimation precision. These results offer valuable insights on and practical guidance for advancing multiparameter estimation in relativistic context.

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