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It is widely known that `collapse of the wave function' on a quantum system A may be brought about by an interaction with another quantum system B. We will prove that this is not just a possible, but a necessary consequence of information…

Quantum Physics · Physics 2007-05-23 Bas Janssens

Recent empirical work in the field of 'weak measurements' has yielded novel ways of more directly accessing and exploring the quantum wavefunction. Measuring either position or momentum for a photon in a 'weak' manner yields a wide range of…

Quantum Physics · Physics 2013-06-17 David R Geelan

We consider realistic measurement systems, where measurements are accompanied by decoherence processes. The aim of this work is the construction of methods and algorithms for precise quantum measurements with fidelity close to the…

Quantum Physics · Physics 2017-01-10 Yu. I. Bogdanov , B. I. Bantysh , N. A. Bogdanova , A. B. Kvasnyy , V. F. Lukichev

Weak measurements may result in extra quantity of quantumness of correlations compared with standard projective measurement on a bipartite quantum state. We show that the quantumness of correlations by weak measurements can be consumed for…

Quantum Physics · Physics 2014-03-18 Lin-Ping Huai , Bo Li , Shi-Xian Qu , Heng Fan

We explore the possibility of using "weak" measurements to carry out quantum state tomography. Given a certain fixed number of copies of identically prepared states of a qubit, we simulate state tomography using weak as well as projective…

Quantum Physics · Physics 2014-08-06 Debmalya Das , Arvind

Coherence and correlation are key features of the quantum system. Quantifying these quantities are astounding task in the framework of resource theory of quantum information processing. In this article, we identify an affinity-based metric…

Quantum Physics · Physics 2021-02-11 R. Muthuganesan , V. K. Chandrasekar , R. Sankaranarayanan

We give an elementary account of quantum measurement and related topics from the modern perspective of decoherence. The discussion should be comprehensible to students who have completed a basic course in quantum mechanics with exposure to…

Quantum Physics · Physics 2022-12-06 Stephen D. H. Hsu

The quantum measurement process by a single-electron transistor or a quantum point contact coupled to a quantum bit is studied. We find a unified description of the statistics of the monitored quantity, the current, in the regime of strong…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Yuriy Makhlin , Gerd Schoen , Alexander Shnirman

The use of qubits as sensitive magnetometers has been studied theoretically and recent demonstrated experimentally. In this paper we propose a generalisation of this concept, where a scanning two-state quantum system is used to probe the…

Quantum Physics · Physics 2009-12-10 J. H. Cole , L. C. L. Hollenberg

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

We analyze the information that one can learn about the state of a quantum two-level system, i.e. a qubit, when probed weakly by a nearby detector. In particular, we focus on the case when the qubit Hamiltonian and the qubit's operator…

Quantum Physics · Physics 2009-08-15 S. Ashhab , J. Q. You , Franco Nori

Quantum coherence is a central ingredient in quantum physics with several theoretical and technological ramifications. In this work we consider a figure of merit encoding the information on how the coherence generated on average by a…

Environment-induced decoherence has long been recognised as being of crucial importance in the study of chaos in quantum systems. In particular, the exact form and strength of the system-environment interaction play a major role in the…

Quantum Physics · Physics 2017-08-02 Jessica K. Eastman , Joseph J. Hope , André R. R. Carvalho

Weak values inferred from weak measurements have been proposed as a tool to investigate trajectories of pre- and post-selected quantum systems. Are the inferences drawn from the weak values about the past of a quantum particle fully true?…

Quantum Physics · Physics 2022-02-10 Rajendra Singh Bhati , Arvind

We can learn (more) about the state a quantum system is in through measurements. We look at how to describe the uncertainty about a quantum system's state conditional on executing such measurements. We show that by exploiting the interplay…

Quantum Physics · Physics 2025-04-22 Keano De Vos , Gert de Cooman

We review results of a recently developed model of a microscopic quantum system interacting with the macroscopic world components which are modeled by collections of bosonic modes. The interaction is via a general operator $\Lambda$ of the…

Quantum Physics · Physics 2010-09-22 Vladimir Privman , Dima Mozyrsky

In a quantum system that is bounded by past and future conditions, weak continuous monitoring forward-evolving and backward-evolving quantum states are usually carried out separately. Therefore, measured signals at a given time t cannot be…

Quantum Physics · Physics 2019-05-20 Le Bin Ho

Quantum sensing utilizes quantum systems as sensors to capture weak signal, and provides new opportunities in nowadays science and technology. The strongest adversary in quantum sensing is decoherence due to the coupling between the sensor…

Quantum Physics · Physics 2020-07-15 Yijin Xie , Jianpei Geng , Huiyao Yu , Xing Rong , Ya Wang , Jiangfeng Du

The formalism of weak measurement in quantum mechanics has revealed profound connections between measurement theory, quantum foundations, and signal processing. In this paper, we develop a pointer-free derivation of superoscillations,…

Quantum Physics · Physics 2025-08-04 Mirco A. Mannucci

The weak values and weak measurement formalism were initially limited to pure states, which were later extended to mixed states, leading to intriguing applications in quantum information processing tasks. Weak values are considered to be…

Quantum Physics · Physics 2025-11-04 Rajendra Singh Bhati