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Measurement based (MB) quantum computation allows for universal quantum computing by measuring individual qubits prepared in entangled multipartite states, known as graph states. Unless corrected for, the randomness of the measurements…

Quantum Physics · Physics 2018-02-28 Rawad Mezher , Joe Ghalbouni , Joseph Dgheim , Damian Markham

Measurements are essential for the processing and protection of information in quantum computers. They can also induce long-range entanglement between unmeasured qubits. However, when post-measurement states depend on many non-deterministic…

In bulk quantum computation one can manipulate a large number of indistinguishable quantum computers by parallel unitary operations and measure expectation values of certain observables with limited sensitivity. The initial state of each…

Quantum Physics · Physics 2009-10-30 Emanuel Knill , Isaac Chuang , Raymond Laflamme

We propose a new method for pure-state and subspace preparation in quantum systems, which employs the output of a continuous measurement process and switching dissipative control to improve convergence speed, as well as robustness with…

Quantum Physics · Physics 2024-06-24 Tommaso Grigoletto , Francesco Ticozzi

Quantum control of an open system is demonstrated employing a thermodynamically consistent master equation. In this framework, the open system dynamics depend on the control protocol due to the dressing of the system by the drive. This…

Quantum Physics · Physics 2022-09-16 Shimshon Kallush , Roie Dann , Ronnie Kosloff

We show the following: a randomly chosen pure state as a resource for measurement-based quantum computation, is - with overwhelming probability - of no greater help to a polynomially bounded classical control computer, than a string of…

Quantum Physics · Physics 2010-10-21 Michael J. Bremner , Caterina Mora , Andreas Winter

The so-called quantum Zeno effect is essentially a consequence of the projection postulate for ideal measurements. To test the effect Itano et al. have performed an experiment on an ensemble of atoms where rapidly repeated level…

Quantum Physics · Physics 2014-11-18 Almut Beige , Gerhard C. Hegerfeldt , Dirk G. Sondermann

This paper considers quantum communication involving an ensemble of states. Apart from the von Neumann entropy, it considers other measures one of which may be useful in obtaining information about an unknown pure state and another that may…

Quantum Physics · Physics 2016-05-11 Subhash Kak

Repetitive measurements can cause freezing of dynamics of a quantum state, which is known as quantum Zeno effect. We consider an interacting one-dimensional fermionic system and study the fate of the many-body quantum Zeno transition if the…

Quantum Physics · Physics 2021-12-08 Ranjan Modak , Debraj Rakshit , Ujjwal Sen

The problem of measurement in quantum mechanics is reanalyzed within a general, strictly probabilistic framework (without reduction postulate). Based on a novel comprehensive definition of measurement the natural emergence of objective…

Quantum Physics · Physics 2007-05-23 Markus Simonius

A rigorous theory of quantum state reduction, the state change of the measured system caused by a measurement conditional upon the outcome of measurement, is developed fully within quantum mechanics without leading to the vicious circle…

Quantum Physics · Physics 2015-06-26 Masanao Ozawa

In classical control theory, tracking refers to the ability to perform measurements and feedback on a classical system in order to enforce some desired dynamics. In this paper we investigate a simple version of quantum tracking, namely, we…

Quantum Physics · Physics 2008-11-20 Paulo E. M. F. Mendonca , Alexei Gilchrist , Andrew C. Doherty

In this paper, we present a general theory of finite quantum measurements, for which we assume that the state space of the measured system is a finite dimensional Hilbert space and that the possible outcomes of a measurement is a finite set…

Quantum Physics · Physics 2023-02-15 Masanao Ozawa

The quantum Zeno effect is a striking feature of quantum mechanics with foundational implications and practical applications in quantum control, error suppression, and error correction. In recent years, the effect has branched off into a…

Quantum Physics · Physics 2025-09-19 Sacha Greenfield , Archana Kamal , Justin Dressel , Eli Levenson-Falk

Ergodic quantum many-body systems undergoing unitary dynamics evolve towards increasingly entangled states characterized by an extensive scaling of entanglement entropy with system volume. At the other extreme, quantum systems repeatedly…

Quantum Physics · Physics 2025-03-11 Jin Ming Koh , Shi-Ning Sun , Mario Motta , Austin J. Minnich

We study the measurement-induced enhancement of the spontaneous decay (called quantum anti-Zeno effect) for a two-level subsystem, where measurements are treated as couplings between the excited state and an auxiliary state rather than the…

Quantum Physics · Physics 2013-07-12 Qing Ai , Dazhi Xu , Su Yi , A. G. Kofman , C. P. Sun , Franco Nori

Coherent control of quantum transitions -- indispensable in quantum technology -- generally relies on the interaction of quantum systems with electromagnetic radiation. Here, we theoretically demonstrate that the non-radiative…

Quantum Physics · Physics 2021-07-14 Dennis Rätzel , Daniel Hartley , Osip Schwartz , Philipp Haslinger

Ising interaction between qubits could produce distortion in entangled pairs generated for engineering purposes (as in quantum computation) in presence of parasite magnetic fields, destroying or altering the expected behavior of process in…

Quantum Physics · Physics 2013-05-29 Francisco Delgado

Quantum information processing relies on precise control of non-classical states in the presence of many uncontrolled environmental degrees of freedom -- requiring careful orchestration of how the relevant degrees of freedom interact with…

Quantum Physics · Physics 2024-02-06 Patrick M. Harrington , Erich Mueller , Kater Murch

In the dynamics of open quantum systems, the interaction with the external environment usually leads to a contraction of the set of reachable states for the system as time increases, eventually shrinking to a single stationary point. In…

Quantum Physics · Physics 2007-09-12 Raffaele Romano