Quantum Metrology Based on Nonclassical Atomic States

2021 ◽  
Vol 30 (3) ◽  
pp. 8-12
Author(s):  
Jae Hoon LEE ◽  
Hyojun SEOK
Keyword(s):  
Quantum Physics ◽  
Quantum Measurements ◽  
Atomic Ensemble ◽  
Collective State ◽  
Quantum Metrology ◽  
Future Prospects ◽  
Measurement Sensitivity ◽  
Crucial Information ◽  
Quantum Technology ◽  
Atomic States

Quantum measurements with atoms have been at the forefront of quantum technology and provide crucial information for a better understanding of quantum physics ever since their conception over a century ago. The universality of the quantized energy states of atoms makes the collective state of an atomic ensemble an outstanding platform for quantum-enhanced metrology. We introduce basic concepts regarding the metrological gain acquired from using nonclassical quantum states via multiparticle entanglement. Current challenges and future prospects for further enhancement of the measurement sensitivity through the use of nonclassical atomic states are discussed with reference to the shot noise and Heisenberg limits.

scholarly journals A variational toolbox for quantum multi-parameter estimation

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Johannes Jakob Meyer ◽  
Johannes Borregaard ◽  
Jens Eisert
Keyword(s):  
Parameter Estimation ◽  
Information Science ◽  
Quantum Algorithms ◽  
Continuous Variable ◽  
General Interest ◽  
Quantum Metrology ◽  
Estimation Problems ◽  
General Parameter ◽  
Quantum Technology ◽  
Aided Design

AbstractWith an ever-expanding ecosystem of noisy and intermediate-scale quantum devices, exploring their possible applications is a rapidly growing field of quantum information science. In this work, we demonstrate that variational quantum algorithms feasible on such devices address a challenge central to the field of quantum metrology: The identification of near-optimal probes and measurement operators for noisy multi-parameter estimation problems. We first introduce a general framework that allows for sequential updates of variational parameters to improve probe states and measurements and is widely applicable to both discrete and continuous-variable settings. We then demonstrate the practical functioning of the approach through numerical simulations, showcasing how tailored probes and measurements improve over standard methods in the noisy regime. Along the way, we prove the validity of a general parameter-shift rule for noisy evolutions, expected to be of general interest in variational quantum algorithms. In our approach, we advocate the mindset of quantum-aided design, exploiting quantum technology to learn close to optimal, experimentally feasible quantum metrology protocols.

scholarly journals A perspective on high photon flux nonclassical light and applications in nonlinear optics

2020 ◽  
Vol 8 ◽  
Author(s):  
Th. Lamprou ◽  
I. Liontos ◽  
N. C. Papadakis ◽  
P. Tzallas
Keyword(s):  
Nonlinear Optics ◽  
Quantum Optics ◽  
Vital Role ◽  
Photon Flux ◽  
Light Sources ◽  
Future Prospects ◽  
Nonclassical Light ◽  
Low Intensity ◽  
High Photon Flux ◽  
Quantum Technology

Abstract Nonclassical light sources have a vital role in quantum optics as they offer a unique resource for studies in quantum technology. However, their applicability is restricted by their low intensity, while the development of new schemes producing intense nonclassical light is a challenging task. In this perspective article, we discuss potential schemes that could be used towards the development of high photon flux nonclassical light sources and their future prospects in nonlinear optics.

scholarly journals CORRELATIONS IN QUANTUM PHYSICS

2012 ◽  
Vol 27 (01n03) ◽  
pp. 1345017 ◽  
Author(s):  
ROSS DORNER ◽  
VLATKO VEDRAL
Keyword(s):  
Quantum Physics ◽  
Quantum Measurements ◽  
Harmonic Oscillators ◽  
Theoretic Analysis ◽  
Information Theoretic ◽  
Coupled Harmonic Oscillators ◽  
Quantum Mutual Information ◽  
Classical Correlations ◽  
The Difference ◽  
Thermodynamic Transformations

We provide a historical perspective of how the notion of correlations has evolved within quantum physics. We begin by reviewing Shannon's information theory and its first application in quantum physics, due to Everett, in explaining the information conveyed during a quantum measurement. This naturally leads us to Lindblad's information theoretic analysis of quantum measurements and his emphasis of the difference between the classical and quantum mutual information. After briefly summarizing the quantification of entanglement using these ideas, we arrive at the concept of quantum discord, which naturally captures the boundary between entanglement and classical correlations. Finally we discuss possible links between discord, which the generation of correlations in thermodynamic transformations of coupled harmonic oscillators.

scholarly journals Non-Gaussian entangled states and quantum metrology with ultracold atomic ensemble

2019 ◽  
Vol 68 (4) ◽  
pp. 040306
Author(s):  
Bo Lu ◽  
Cheng-Yin Han ◽  
Min Zhuang ◽  
Yong-Guan Ke ◽  
Jia-Hao Huang ◽  
...  
Keyword(s):  
Entangled States ◽  
Atomic Ensemble ◽  
Quantum Metrology ◽  
Non Gaussian

Application: Sensing Time, Motion, and Gravity with Quantum Technology

2017 ◽  
Author(s):  
Michael G. Raymer
Keyword(s):  
Quantum Physics ◽  
New Technologies ◽  
Classical Physics ◽  
Time Motion ◽  
Quantum Technology ◽  
Sensing Time

What are quantum physics–based sensing technologies? Quantum physics–based sensing technologies are those that rely on quantum physics principles for their working. If classical physics were the whole story, we would not have access to these new technologies. In Chapter 5, I introduced...

scholarly journals Evolution of Complexity in Out-of-Equilibrium Systems by Time-Resolved or Space-Resolved Synchrotron Radiation Techniques

2019 ◽  
Vol 4 (1) ◽  
pp. 32 ◽  
Author(s):  
Gaetano Campi ◽  
Antonio Bianconi
Keyword(s):  
Synchrotron Radiation ◽  
Quantum Physics ◽  
Materials Science ◽  
High Temperature Superconductivity ◽  
Supramolecular Assembly ◽  
Time Resolved ◽  
Experimental Approaches ◽  
Synchrotron Radiation Techniques ◽  
Structural Fluctuations ◽  
Quantum Technology

Out-of-equilibrium phenomena are attracting high interest in physics, materials science, chemistry and life sciences. In this state, the study of structural fluctuations at different length scales in time and space are necessary to achieve significant advances in the understanding of the structure-functionality relationship. The visualization of patterns arising from spatiotemporal fluctuations is nowadays possible thanks to new advances in X-ray instrumentation development that combine high-resolution both in space and in time. We present novel experimental approaches using high brilliance synchrotron radiation sources, fast detectors and focusing optics, joint with advanced data analysis based on automated statistical, mathematical and imaging processing tools. This approach has been used to investigate structural fluctuations in out-of-equilibrium systems in the novel field of inhomogeneous quantum complex matter at the crossing point of technology, physics and biology. In particular, we discuss how nanoscale complexity controls the emergence of high-temperature superconductivity (HTS), myelin functionality and formation of hybrid organic-inorganic supramolecular assembly. The emergent complex geometries, opening novel venues to quantum technology and to the development of quantum physics of living systems, are discussed.

scholarly journals An experimental test of the geodesic rule proposition for the noncyclic geometric phase

2020 ◽  
Vol 6 (9) ◽  
pp. eaay8345 ◽  
Author(s):  
Zhifan Zhou ◽  
Yair Margalit ◽  
Samuel Moukouri ◽  
Yigal Meir ◽  
Ron Folman
Keyword(s):  
General Relativity ◽  
Geometric Phase ◽  
Quantum Physics ◽  
Matter Wave ◽  
Experimental Demonstration ◽  
Central Concept ◽  
Sign Change ◽  
Quantum Technology ◽  
Potential Use ◽  
Phase Space Trajectory

The geometric phase due to the evolution of the Hamiltonian is a central concept in quantum physics and may become advantageous for quantum technology. In noncyclic evolutions, a proposition relates the geometric phase to the area bounded by the phase-space trajectory and the shortest geodesic connecting its end points. The experimental demonstration of this geodesic rule proposition in different systems is of great interest, especially due to the potential use in quantum technology. Here, we report a previously unshown experimental confirmation of the geodesic rule for a noncyclic geometric phase by means of a spatial SU(2) matter-wave interferometer, demonstrating, with high precision, the predicted phase sign change and π jumps. We show the connection between our results and the Pancharatnam phase. Last, we point out that the geodesic rule may be applied to obtain the red shift in general relativity, enabling a new quantum tool to measure gravity.

scholarly journals Quantum measurements and contextuality

2019 ◽  
Vol 377 (2157) ◽  
pp. 20190033 ◽  
Author(s):  
Robert B. Griffiths
Keyword(s):  
Quantum Mechanics ◽  
Probability Distribution ◽  
Quantum Physics ◽  
Joint Probability ◽  
Quantum Measurements ◽  
Joint Probability Distribution ◽  
Theme Issue ◽  
Different Types ◽  
Consistent Manner ◽  
Quantum Observables

In quantum physics, the term ‘contextual’ can be used in more than one way. One usage, here called ‘Bell contextual’ since the idea goes back to Bell, is that if A , B and C are three quantum observables, with A compatible (i.e. commuting) with B and also with C , whereas B and C are incompatible, a measurement of A might yield a different result (indicating that quantum mechanics is contextual) depending upon whether A is measured along with B (the { A ,  B } context) or with C (the { A ,  C } context). An analysis of what projective quantum measurements measure shows that quantum theory is Bell non-contextual: the outcome of a particular A measurement when A is measured along with B would have been exactly the same if A had, instead, been measured along with C . A different definition, here called ‘globally (non)contextual’ refers to whether or not there is (non-contextual) or is not (contextual) a single joint probability distribution that simultaneously assigns probabilities in a consistent manner to the outcomes of measurements of a certain collection of observables, not all of which are compatible. A simple example shows that such a joint probability distribution can exist even in a situation where the measurement probabilities cannot refer to properties of a quantum system, and hence lack physical significance, even though mathematically well defined. It is noted that the quantum sample space, a projective decomposition of the identity, required for interpreting measurements of incompatible properties in different runs of an experiment using different types of apparatus, has a tensor product structure, a fact sometimes overlooked. This article is part of the theme issue ‘Contextuality and probability in quantum mechanics and beyond’.

Quantenphysik Und Quantentechnologie / Quantum Physics And Quantum Technology

2015 ◽  
Author(s):  
Thorsten Schumm ◽  
Johannes Majer ◽  
Peter Rabl ◽  
Arno Rauschenbeutel ◽  
Hannes-Jörg Schmiedmayer
Keyword(s):  
Quantum Physics ◽  
Quantum Technology
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