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The evolution of a quantum system comprises two fundamental processes--continuous unitary dynamics and stochastic measurement-induced jumps. The latter are often viewed as a source of decoherence. Can two histories of such an evolution,…

Quantum Physics · Physics 2026-05-25 Parveen Kumar , Igor V. Gornyi , Yuval Gefen

We argue from the point of view of statistical inference that the quantum relative entropy is a good measure for distinguishing between two quantum states (or two classes of quantum states) described by density matrices. We extend this…

Quantum Physics · Physics 2009-10-30 V. Vedral , M. B. Plenio , K. Jacobs , P. L. Knight

Measurement has a special role in quantum theory: by collapsing the wavefunction it can enable phenomena such as teleportation and thereby alter the "arrow of time" that constrains unitary evolution. When integrated in many-body dynamics,…

Quantum Physics · Physics 2023-10-24 Jesse C. Hoke , Matteo Ippoliti , Eliott Rosenberg , Dmitry Abanin , Rajeev Acharya , Trond I. Andersen , Markus Ansmann , Frank Arute , Kunal Arya , Abraham Asfaw , Juan Atalaya , Joseph C. Bardin , Andreas Bengtsson , Gina Bortoli , Alexandre Bourassa , Jenna Bovaird , Leon Brill , Michael Broughton , Bob B. Buckley , David A. Buell , Tim Burger , Brian Burkett , Nicholas Bushnell , Zijun Chen , Ben Chiaro , Desmond Chik , Josh Cogan , Roberto Collins , Paul Conner , William Courtney , Alexander L. Crook , Ben Curtin , Alejandro Grajales Dau , Dripto M. Debroy , Alexander Del Toro Barba , Sean Demura , Augustin Di Paolo , Ilya K. Drozdov , Andrew Dunsworth , Daniel Eppens , Catherine Erickson , Edward Farhi , Reza Fatemi , Vinicius S. Ferreira , Leslie Flores Burgos , Ebrahim Forati , Austin G. Fowler , Brooks Foxen , William Giang , Craig Gidney , Dar Gilboa , Marissa Giustina , Raja Gosula , Jonathan A. Gross , Steve Habegger , Michael C. Hamilton , Monica Hansen , Matthew P. Harrigan , Sean D. Harrington , Paula Heu , Markus R. Hoffmann , Sabrina Hong , Trent Huang , Ashley Huff , William J. Huggins , Sergei V. Isakov , Justin Iveland , Evan Jeffrey , Cody Jones , Pavol Juhas , Dvir Kafri , Kostyantyn Kechedzhi , Tanuj Khattar , Mostafa Khezri , Mária Kieferová , Seon Kim , Alexei Kitaev , Paul V. Klimov , Andrey R. Klots , Alexander N. Korotkov , Fedor Kostritsa , John Mark Kreikebaum , David Landhuis , Pavel Laptev , Kim-Ming Lau , Lily Laws , Joonho Lee , Kenny W. Lee , Yuri D. Lensky , Brian J. Lester , Alexander T. Lill , Wayne Liu , Aditya Locharla , Orion Martin , Jarrod R. McClean , Matt McEwen , Kevin C. Miao , Amanda Mieszala , Shirin Montazeri , Alexis Morvan , Ramis Movassagh , Wojciech Mruczkiewicz , Matthew Neeley , Charles Neill , Ani Nersisyan , Michael Newman , Jiun H. Ng , Anthony Nguyen , Murray Nguyen , Murphy Yuezhen Niu , Tom E. O'Brien , Seun Omonije , Alex Opremcak , Andre Petukhov , Rebecca Potter , Leonid P. Pryadko , Chris Quintana , Charles Rocque , Nicholas C. Rubin , Negar Saei , Daniel Sank , Kannan Sankaragomathi , Kevin J. Satzinger , Henry F. Schurkus , Christopher Schuster , Michael J. Shearn , Aaron Shorter , Noah Shutty , Vlad Shvarts , Jindra Skruzny , W. Clarke Smith , Rolando D. Somma , George Sterling , Douglas Strain , Marco Szalay , Alfredo Torres , Guifre Vidal , Benjamin Villalonga , Catherine Vollgraff Heidweiller , Ted White , Bryan W. K. Woo , Cheng Xing , Z. Jamie. Yao , Ping Yeh , Juhwan Yoo , Grayson Young , Adam Zalcman , Yaxing Zhang , Ningfeng Zhu , Nicholas Zobrist , Harmut Neven , Ryan Babbush , Dave Bacon , Sergio Boixo , Jeremy Hilton , Erik Lucero , Anthony Megrant , Julian Kelly , Yu Chen , Vadim Smelyanskiy , Xiao Mi , Vedika Khemani , Pedram Roushan

Measurements provide a novel mechanism for generating the entanglement resource necessary for performing scalable quantum computation. Recently, we proposed a method for performing parity measurements in a coupled quantum dot system. In…

Quantum Physics · Physics 2009-11-13 Avinash Kolli , Simon C. Benjamin , Brendon W. Lovett , Thomas M. Stace

Quantum computers have the potential to solve certain interesting problems significantly faster than classical computers. To exploit the power of a quantum computation it is necessary to perform inter-qubit operations and generate entangled…

Mesoscale and Nanoscale Physics · Physics 2013-04-09 Michael D. Shulman , Oliver E. Dial , Shannon P. Harvey , Hendrik Bluhm , Vladimir Umansky , Amir Yacoby

We analyze a quantum measurement where the apparatus is initially in a mixed state. We show that the amount of information gained in a measurement is not equal to the amount of entanglement between the system and the apparatus, but is…

Quantum Physics · Physics 2009-11-07 V. Vedral

Quantum entanglement is affected by unitary evolution, which spreads the entanglement through the whole system, and also by measurements, which usually tends to disentangle subsystems from the rest. Their competition has been known to…

Quantum Physics · Physics 2025-06-24 Haifeng Tang , Hong-Yi Wang , Zhong Wang , Xiao-Liang Qi

While entanglement between distant parties has been extensively studied, entangled measurements have received relatively little attention despite their significance in understanding non-locality and their central role in quantum computation…

Quantum Physics · Physics 2024-10-08 Flavio Del Santo , Jakub Czartowski , Karol Życzkowski , Nicolas Gisin

We use hyper-entanglement to experimentally realize deterministic entanglement swapping based on quantum Elegant Joint Measurements. These are joint projections of two qubits onto highly symmetric, iso-entangled, bases. We report…

Dense coding is the seminal example of how entanglement can boost qubit communication, from sending one bit to sending two bits. This is made possible by projecting separate particles onto a maximally entangled basis. We investigate more…

Entanglement is considered to be one of the most profound features of quantum mechanics. An entangled state of a system consisting of two subsystems cannot be described as a product of the quantum states of the two subsystems. In this sense…

Quantum Physics · Physics 2009-11-07 Brian Julsgaard , Alexander Kozhekin , Eugene S. Polzik

Experimental determination of entanglement is important not only to characterize the state and use it in quantum information, but also in understanding complicated phenomena such as phase transitions. In this paper we show that in many…

Quantum Physics · Physics 2016-01-20 Gaurav Chaudhary , V. Ravishankar

We show that the expectation value of squared correlations measured along random local directions is an identifier of quantum entanglement in pure states which can be directly experimentally assessed if two copies of the state were…

Quantum Physics · Physics 2015-11-18 Minh Cong Tran , Borivoje Dakic , Francois Arnault , Wieslaw Laskowski , Tomasz Paterek

The ability to perform a universal set of quantum operations based solely on static resources and measurements presents us with a strikingly novel viewpoint for thinking about quantum computation and its powers. We consider the two major…

Quantum Physics · Physics 2007-05-23 Panos Aliferis , Debbie W. Leung

In the present study we revisit the application of the $q$-information measures $R_q$ of R\'enyi's and $S_q$ of Tsallis' to the discussion of special features of two qubits systems. More specifically, we study the correlations between the…

Quantum Physics · Physics 2015-06-26 J. Batle , M. Casas , A. Plastino , A. R. Plastino

Quantum properties of the probes used to estimate a classical parameter can be used to attain accuracies that beat the standard quantum limit. When qubits are used to construct a quantum probe, it is known that initializing $n$ qubits in an…

Quantum Physics · Physics 2009-11-13 Anil Shaji , Carlton M. Caves

The paradigm of measurement-based quantum computation opens new experimental avenues to realize a quantum computer and deepens our understanding of quantum physics. Measurement-based quantum computation starts from a highly entangled…

If there are correlations between two qubits then the results of the measurement on one of them can help to predict measurement results on the other one. It is an interesting question what can be predicted about the results of two…

Quantum Physics · Physics 2016-09-08 R. Filip , M. Gavenda , J. Soubusta , A. Cernoch , M. Dusek

We demonstrate by an explicit model calculation that the decay of entanglement of two two-state systems (two qubits) is governed by the product of the factors that measure the degree of decoherence of each of the qubits, subject to…

Quantum Physics · Physics 2010-10-12 D. Tolkunov , V. Privman , P. K. Aravind

The measurement process is considered for quantum field theory on curved spacetimes. Measurements are carried out on one QFT, the "system", using another, the "probe" via a dynamical coupling of "system" and "probe" in a bounded spacetime…

Mathematical Physics · Physics 2020-07-27 Christopher J. Fewster , Rainer Verch