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Entangled states, like the two-mode squeezed vacuum state, are known to give quantum advantage in the illumination protocol, a method to detect a weakly reflecting target submerged in a thermal background. We use non-Gaussian photon-added…

Quantum Physics · Physics 2024-04-03 Rivu Gupta , Saptarshi Roy , Tamoghna Das , Aditi Sen De

Quantum metrology exploits quantum mechanical laws to improve the precision in estimating technologically relevant parameters such as phase, frequency, or magnetic fields. Probe states are usually tailored on the particular dynamics whose…

In the Unruh effect an observer with constant acceleration perceives the quantum vacuum as thermal radiation. The Unruh effect has been believed to be a pure quantum phenomenon, but here we show theoretically how the effect arises from the…

General Relativity and Quantum Cosmology · Physics 2018-08-22 Ulf Leonhardt , Itay Griniasty , Sander Wildeman , Emmanuel Fort , Mathias Fink

We propose a method for simulating an Unruh-DeWitt detector, coupled to a 1+1-dimensional massless scalar field, with a suitably-engineered $\chi^{(2)}$ nonlinear interaction. In this simulation, the parameter playing the role of the…

Quantum Physics · Physics 2020-09-17 Eugene Adjei , Kevin J. Resch , Agata M. Brańczyk

In this paper we investigate the connection between quantum information theory and machine learning. In particular, we show how quantum state discrimination can represent a useful tool to address the standard classification problem in…

We provide the optimal measurement strategy for a class of noisy channels that reduce to the identity channel for a specific value of a parameter (spreading channels). We provide an example that is physically relevant: the estimation of the…

Quantum Physics · Physics 2022-12-21 Wojciech Górecki , Alberto Riccardi , Lorenzo Maccone

Near-term quantum computers are noisy, and therefore must run algorithms with a low circuit depth and qubit count. Here we investigate how noise affects a quantum neural network (QNN) for state discrimination, applicable on near-term…

Quantum Physics · Physics 2021-01-27 Andrew Patterson , Hongxiang Chen , Leonard Wossnig , Simone Severini , Dan Browne , Ivan Rungger

We obtained an exact solution for a uniformly accelerated Unruh-DeWitt detector interacting with a massless scalar field in (3+1) dimensions which enables us to study the entire evolution of the total system, from the initial transient to…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Shih-Yuin Lin , B. L. Hu

The Unruh effect predicts a thermal response for an accelerated detector moving through the vacuum. Here we propose an interferometric scheme to observe an analogue of the circular Unruh effect using a localized laser coupled to a…

General Relativity and Quantum Cosmology · Physics 2020-12-22 Cisco Gooding , Steffen Biermann , Sebastian Erne , Jorma Louko , William G. Unruh , Joerg Schmiedmayer , Silke Weinfurtner

We derive the optimal measurement for quantum state discrimination without a priori probabilities, i.e. in a minimax strategy instead of the usually considered Bayesian one. We consider both minimal-error and unambiguous discrimination…

Quantum Physics · Physics 2025-04-02 Giacomo Mauro D'Ariano , Massimiliano Federico Sacchi , Jonas Kahn

A long-standing debate on Unruh effect is about its obscure thermal nature. In this Letter, we use quantum Fisher information (QFI) as an effective probe to explore the thermal nature of Unruh effect from both local and global perspectives.…

High Energy Physics - Theory · Physics 2022-03-02 Jun Feng , Jing-Jun Zhang

In this thesis we focus on the influence of uniform acceleration on quantum states and their properties, as well as on quantum entanglement contained in the vacuum. First, we analyze a quantum clock measuring time in terms of the decay of…

Quantum Physics · Physics 2019-08-19 Krzysztof Lorek

Deterministic discrimination of nonorthogonal states is forbidden by quantum measurement theory. However, if we do not want to succeed all the time, i.e. allow for inconclusive outcomes to occur, then unambiguous discrimination becomes…

Quantum Physics · Physics 2009-11-11 Janos Bergou , Ulrike Herzog , Mark Hillery

In a relativistic theory of quantum information, the possible presence of horizons is a complicating feature placing restrictions on the transmission and retrieval of information. We consider two inertial participants communicating via a…

Quantum Physics · Physics 2009-09-28 Kamil Bradler , Patrick Hayden , Prakash Panangaden

We present an application of particle statistics to the problem of optimal ambiguous discrimination of quantum states. The states to be discriminated are encoded in the internal degrees of freedom of identical particles, and we use the…

Quantum Physics · Physics 2009-11-10 S. Bose , A. Ekert , Y. Omar , N. Paunkovic , V. Vedral

Single quantum system, such as Unruh-DeWitt detector, can be used to determine absolute acceleration by local measurements on a quantum field. To show this, we consider two kinematically indistinguishable scenarios: an inertial observer,…

Quantum Physics · Physics 2011-05-09 Andrzej Dragan , Ivette Fuentes , Jorma Louko

We analyze the entanglement between two modes of a free Dirac field as seen by two relatively accelerated parties. The entanglement is degraded by the Unruh effect and asymptotically reaches a non-vanishing minimum value in the infinite…

Quantum Physics · Physics 2009-11-13 P. M. Alsing , I. Fuentes-Schuller , R. B. Mann , T. E. Tessier

The Unruh effect predicts that an accelerated observer perceives the Minkowski vacuum as a thermal bath, but its direct observation requires extreme accelerations beyond current experimental reach. Foundational theory [Olson & Ralph, Phys.…

Quantum Physics · Physics 2025-10-29 Zhenghao Luo , Yi Li , Xingyu Zhao , Zihan Xie , Zehua Tian , Yiheng Lin

In this paper, we propose an iterative algorithm using polar decomposition to approximate a channel characterized by a single unitary matrix based on input-output quantum state pairs. In limited data, we state and prove that the optimal…

Numerical Analysis · Mathematics 2025-06-27 Matthew M. Lin , Hao-Wei Huang , Bing-Ze Lu

We address the problem of estimating the mass of a quantum particle in a gravitational field and seek the ultimate bounds to precision of quantum-limited detection schemes. In particular, we study the effect of the field on the achievable…

General Relativity and Quantum Cosmology · Physics 2017-05-24 Luigi Seveso , Valerio Peri , Matteo G. A. Paris