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Event synchronisation is a ubiquitous task, with applications ranging from 5G technology to industrial automation and smart power grids. The emergence of quantum communication networks will further increase the demand for precise…

We experimentally realize a quantum clock by using a charge sensor to count charges tunneling through a double quantum dot (DQD). Individual tunneling events are used as the clock's ticks. We quantify the clock's precision while measuring…

The use of entangled light to illuminate objects is shown to provide significant enhancements over unentangled light for detecting and imaging those objects in the presence of high levels of noise and loss. Each signal sent out is entangled…

Quantum Physics · Physics 2008-03-14 Seth Lloyd

Squeezing of quantum fluctuations by means of entanglement is a well recognized goal in the field of quantum information science and precision measurements. In particular, squeezing the fluctuations via entanglement between two-level atoms…

Quantum Physics · Physics 2009-11-25 J. Appel , P. J. Windpassinger , D. Oblak , U. B. Hoff , N. Kjaergaard , E. S. Polzik

Recently, the fast development of quantum technologies led to the need for tools allowing the characterization of quantum resources. In particular, the ability to estimate non-classical aspects, e.g. entanglement and quantum discord, in…

All clocks, in some form or another, use the evolution of nature towards higher entropy states to quantify the passage of time. Due to the statistical nature of the second law and corresponding entropy flows, fluctuations fundamentally…

Mesoscale and Nanoscale Physics · Physics 2021-05-12 A. N. Pearson , Y. Guryanova , P. Erker , E. A. Laird , G. A. D. Briggs , M. Huber , N. Ares

A satellite-based scheme to perform clock synchronization between ground stations spread across the globe using quantum resources was proposed in [Phys. Rev. A 107, 022615 (2023)], based on the quantum clock synchronization (QCS) protocol…

Quantum Physics · Physics 2023-06-16 Stav Haldar , Ivan Agullo , James E. Troupe

We derive the predicted time dilation of delocalized atomic clocks in an optical lattice setup in the presence of a gravitational field to leading order in quantum relativistic corrections. We investigate exotic quantum states of motion…

Quantum Physics · Physics 2025-07-29 Yanglin Hu , Maximilian P. E. Lock , Mischa P. Woods

Recent experiments to test Bell's inequality using entangled photons and ions aimed at tests of basic quantum mechanical principles. Interesting results have been obtained and many loopholes could be closed. In this paper we want to point…

Quantum Physics · Physics 2015-06-26 Dimitris G. Angelakis , Almut Beige , Peter L. Knight , William J. Munro , Ben Tregenna

Increasingly sophisticated quantum computers motivate the exploration of their abilities in certifying genuine quantum phenomena. Here, we demonstrate the power of state-of-the-art IBM quantum computers in correlation experiments inspired…

Quantum Physics · Physics 2021-07-28 Elisa Bäumer , Nicolas Gisin , Armin Tavakoli

We have developed a scheme to generate, control, transmit and measure entangled photonic qutrits (two photons each of dimension d = 3). A Bell test of this source has previously been reported elsewhere [1], therefore, here we focus on how…

Quantum Physics · Physics 2009-11-10 R. T. Thew , S. Tanzilli , A. Acin , H. Zbinden , N. Gisin

It is often conjectured that quantum synchronisation and entanglement are two independent properties which two coupled quantum systems may not exhibit at the same time. However, as both these properties can be understood in terms of the…

Quantum Physics · Physics 2023-05-09 Devender Garg , Manju , Shubhrangshu Dasgupta , Asoka Biswas

A wide variety of positioning and ranging procedures are based on repeatedly sending electromagnetic pulses through space and measuring their time of arrival. This paper shows that quantum entanglement and squeezing can be employed to…

Quantum Physics · Physics 2009-11-07 V. Giovannetti , S. Lloyd , L. Maccone

We use a quantum non-demolition measurement to generate a spin squeezed state and to create entanglement in a cloud of 10^5 cold cesium atoms, and for the first time operate an atomic clock improved by spin squeezing beyond the projection…

Quantum metrology utilizes entanglement for improving the sensitivity of measurements. Up to now the focus has been on the measurement of just one out of two non-commuting observables. Here we demonstrate a laser interferometer that…

Measurements in the quantum domain can exceed classical notions. This concerns fundamental questions about the nature of the measurement process itself, as well as applications, such as their function as building blocks of quantum…

Quantum Physics · Physics 2023-02-02 Jan Sperling , Ilaria Gianani , Marco Barbieri , Elizabeth Agudelo

Classical clocks measure proper time along their worldline, and Riemannian geometry provides tools for predicting the time shown by clocks in both flat and curved spacetimes. Common approaches to time in quantum systems, based for instance…

General Relativity and Quantum Cosmology · Physics 2025-01-14 Joseph Balsells , Martin Bojowald

A promising practical application of entanglement is metrology, where quantum states can be used to make measurements beyond the shot noise limit. Here we consider how metrology schemes could be realised using atomic Bose-Einstein…

Quantum Physics · Physics 2015-05-27 J. A. Dunningham , J. J. Cooper , D. W. Hallwood

It has been discussed recently how quantum illumination can be used to increase the accuracy of the value range-delay measurement \cite{Zhuang Shapiro 2022} in the domain of SNR compatible with current radar systems. However, the advantage…

Quantum Physics · Physics 2023-05-10 Ricardo Gallego Torromé

We introduce methods for clock synchronization that make use of the adiabatic exchange of nondegenerate two-level quantum systems: ticking qubits. Schemes involving the exchange of N independent qubits with frequency $\omega$ give a…

Quantum Physics · Physics 2016-09-08 Mark de Burgh , Stephen D. Bartlett