M. Barbieri, A. Datta, T. Bartley, Xian-min Jin, W. Kolthammer, I. Walmsley
{"title":"Quantum enhanced estimation of optical detector efficiencies","authors":"M. Barbieri, A. Datta, T. Bartley, Xian-min Jin, W. Kolthammer, I. Walmsley","doi":"10.1515/qmetro-2016-0002","DOIUrl":"https://doi.org/10.1515/qmetro-2016-0002","url":null,"abstract":"Abstract Quantum mechanics establishes the ultimate limit to the scaling of the precision on any parameter, by identifying optimal probe states and measurements. While this paradigm is, at least in principle, adequate for the metrology of quantum channels involving the estimation of phase and loss parameters, we show that estimating the loss parameters associated with a quantum channel and a realistic quantum detector are fundamentally different. While Fock states are provably optimal for the former, we identify a crossover in the nature of the optimal probe state for estimating detector imperfections as a function of the loss parameter using Fisher information as a benchmark. We provide theoretical results for on-off and homodyne detectors, the most widely used detectors in quantum photonics technologies, when using Fock states and coherent states as probes.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"163 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133596750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Intensity correlations from linear interactions","authors":"M. Bina, S. Olivares","doi":"10.2478/qmetro-2014-0004","DOIUrl":"https://doi.org/10.2478/qmetro-2014-0004","url":null,"abstract":"Abstract We address the generation of intensity correlations arising from the interference between two optical states interacting through a beam splitter. We consider both phase insensitive and sensitive states and write the intensity correlations as functions of the mean number of photons and field quadratures of the input states. In particular we consider Fock number states and squeezed states as a paradigm of non-classical states and mixture of coherent states, which can be experimentally accessible. We show that, under certain conditions on the input states, intensity correlations may vanish or turn into anticorrelations.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117038379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Weak-value amplification: state of play","authors":"G. Knee, J. Combes, C. Ferrie, E. Gauger","doi":"10.1515/qmetro-2016-0006","DOIUrl":"https://doi.org/10.1515/qmetro-2016-0006","url":null,"abstract":"Abstract Weak values arise in quantum theory when the result of a weak measurement is conditioned on a subsequent strong measurement. The majority of the trials are discarded, leaving only very few successful events. Intriguingly those can display a substantial signal amplification. This raises the question of whether weak values carry potential to improve the performance of quantum sensors, and indeed a number of impressive experimental results suggested this may be the case. By contrast, recent theoretical studies have found the opposite: using weak-values to obtain an amplification generally worsens metrological performance. This survey summarises the implications of those studies, which call for a reappraisal of weak values’ utility and for further work to reconcile theory and experiment.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128260109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Rogers, N. Gullo, G. Chiara, G. Palma, M. Paternostro
{"title":"Hybrid optomechanics for Quantum Technologies","authors":"B. Rogers, N. Gullo, G. Chiara, G. Palma, M. Paternostro","doi":"10.2478/qmetro-2014-0002","DOIUrl":"https://doi.org/10.2478/qmetro-2014-0002","url":null,"abstract":"Abstract We review the physics of hybrid optomechanical systems consisting of a mechanical oscillator interacting with both a radiation mode and an additional matterlike system. We concentrate on the cases embodied by either a single or a multi-atom system (a Bose-Einstein condensate, in particular) and discuss a wide range of physical effects, from passive mechanical cooling to the set-up of multipartite entanglement, from optomechanical nonlocality to the achievement of non-classical states of a single mechanical mode. The reviewed material showcases the viability of hybridised cavity optomechanical systems as basic building blocks for quantum communication networks and quantum state-engineering devices, possibly empowered by the use of quantum and optimal control techniques. The results that we discuss are instrumental to the promotion of hybrid optomechanical devices as promising experimental platforms for the study of nonclassicality at the genuine mesoscopic level.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125070620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Gaussian and Non-Gaussian operations on non-Gaussian state: engineering non-Gaussianity","authors":"S. Olivares, A. Allevi, M. Bondani","doi":"10.2478/qmetro-2014-0001","DOIUrl":"https://doi.org/10.2478/qmetro-2014-0001","url":null,"abstract":"Abstract Multiple photon subtraction applied to a displaced phase-averaged coherent state, which is a non-Gaussian classical state, produces conditional states with a non trivial (positive) Glauber-Sudarshan Prepresentation. We theoretically and experimentally demonstrate that, despite its simplicity, this class of conditional states cannot be fully characterized by direct detection of photon numbers. In particular, the non-Gaussianity of the state is a characteristics that must be assessed by phase-sensitive measurements. We also show that the non-Gaussianity of conditional states can be manipulated by choosing suitable conditioning values and composition of phase-averaged states.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134061600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Informationally incomplete quantum tomography","authors":"Y. S. Teo, J. Řeháček, Z. Hradil","doi":"10.2478/qmetro-2013-0006","DOIUrl":"https://doi.org/10.2478/qmetro-2013-0006","url":null,"abstract":"Abstract In quantum-state tomography on sources with quantum degrees of freedom of large Hilbert spaces, inference of quantum states of light for instance, a complete characterization of the quantum states for these sources is often not feasible owing to limited resources. As such, the concepts of informationally incomplete state estimation becomes important. These concepts are ideal for applications to quantum channel/ process tomography, which typically requires a much larger number of measurement settings for a full characterization of a quantum channel. Some key aspects of both quantumstate and quantum-process tomography are arranged together in the form of a tutorial review article that is catered to students and researchers who are new to the field of quantum tomography, with focus on maximum-likelihood related techniques as instructive examples to illustrate these ideas.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127969086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Testing quantum mechanics: a statistical approach","authors":"M. Tsang","doi":"10.2478/qmetro-2013-0007","DOIUrl":"https://doi.org/10.2478/qmetro-2013-0007","url":null,"abstract":"Abstract As experiments continue to push the quantum-classical boundary using increasingly complex dynamical systems, the interpretation of experimental data becomes more and more challenging: when the observations are noisy, indirect, and limited, how can we be sure that we are observing quantum behavior? This tutorial highlights some of the difficulties in such experimental tests of quantum mechanics, using optomechanics as the central example, and discusses how the issues can be resolved using techniques from statistics and insights from quantum information theory.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124017797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Z. Shadman, H. Kampermann, Chiara Macchiavello, D. Bruß
{"title":"A review on super dense coding over covariant noisy channels","authors":"Z. Shadman, H. Kampermann, Chiara Macchiavello, D. Bruß","doi":"10.2478/qmetro-2013-0004","DOIUrl":"https://doi.org/10.2478/qmetro-2013-0004","url":null,"abstract":"Abstract We study the performance of the super dense coding protocol in the presence of quantum channels with covariant noise. We first consider the bipartite case and review in a unified way the case of general Pauli channels. We discuss both the cases of unitary and non-unitary encoding. We also study the multipartite scenario and investigate the case of many senders and one receiver.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122755094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Coherently enhanced measurements in classical mechanics","authors":"D. Braun, S. Popescu","doi":"10.2478/qmetro-2014-0003","DOIUrl":"https://doi.org/10.2478/qmetro-2014-0003","url":null,"abstract":"Abstract In all quantitative sciences, it is common practice to increase the signal-to-noise ratio of noisy measurements by measuring identically prepared systems N times and averaging the measurement results. This leads to a scaling of the sensitivity as 1/√N, known in quantum measurement theory as the “standard quantum limit” (SQL). It is known that if one puts the N systems into an entangled state, a scaling as 1/N can be achieved, the socalled “Heisenberg limit” (HL), but decoherence problems have so far prevented implementation of such protocols for large N. Here we show that a method of coherent averaging inspired by a recent entanglement-free quantum enhanced measurement protocol is capable of achieving a sensitivity that scales as 1/N in a purely classical setup. This may substantially improve the measurement of very weak interactions in the classical realm, and, in particular, open a novel route to measuring the gravitational constant with enhanced precision.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114442960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Vidrighin, T. Bartley, G. Donati, Xian-min Jin, M. Barbieri, W. Kolthammer, A. Datta, I. Walmsley
{"title":"Requirements for two-source entanglement concentration","authors":"M. Vidrighin, T. Bartley, G. Donati, Xian-min Jin, M. Barbieri, W. Kolthammer, A. Datta, I. Walmsley","doi":"10.2478/qmetro-2013-0002","DOIUrl":"https://doi.org/10.2478/qmetro-2013-0002","url":null,"abstract":"Abstract Entanglement enhancement is a key task for quantum technologies. This operation performed on states produced by parametric down-conversion sources has been the object of several recent experimental investigations. In particular, conditional preparation by photon-subtraction has been shown to improve the entanglement of these states. Here we analyse the role played by non-Gaussian and Gaussian measurements in more general entanglement concentration operations performed on a pair of two-mode squeezed vacua. We find stringent requirements for achieving an improved entanglement enhancement by measuring jointly these two resource states.","PeriodicalId":421179,"journal":{"name":"Quantum Measurements and Quantum Metrology","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133540829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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