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Precision control of a quantum system requires accurate determination of the effective system Hamiltonian. We develop a method for estimating the Hamiltonian parameters for some unknown two-state system and providing uncertainty bounds on…

To quantify the effect of decoherence in quantum measurements, it is desirable to measure not merely the square modulus of the spatial wavefunction, but the entire density matrix, whose phases carry information about momentum and how pure…

Quantum Physics · Physics 2009-10-30 Max Tegmark

We propose a state estimation scheme for spins, using a modified setup of the Stern-Gerlach experiment, in which a beam of neutral spin-1/2 point particles interacts with a quadrupolar magnetic field. The proposed linear inversion…

Quantum Physics · Physics 2021-04-07 Javier Martínez-Cifuentes , K. M. Fonseca-Romero

We investigate the behavior of genuine multiparticle entanglement, as quantified by the generalized geometric measure, in gapless-to-gapped quantum transitions of one- and two-dimensional quantum spin models. The investigations are…

Quantum Physics · Physics 2014-09-09 Anindya Biswas , R. Prabhu , Aditi Sen De , Ujjwal Sen

In the Stern--Gerlach (SG) apparatus, when the filtering is not perfect, the fermion state transformation is done by non-ideal devices. Such an apparatus is described in quantum mechanics by quantum instruments. It will be shown how the…

Quantum Physics · Physics 2025-11-20 Ioan Sturzu

Experimental observation of the decoherence of macroscopic objects is of fundamental importance to the study of quantum collapse models and the quantum to classical transition. Optomechanics is a promising field for the study of such models…

Quantum Physics · Physics 2018-06-20 Matthew J. Weaver , David Newsom , Fernando Luna , Wolfgang Löffler , Dirk Bouwmeester

In his Comment on a recent paper by two of us Kominis claims that the recently proposed quantum measurement model for spin-selective reactions of radical pairs leads to ambiguous predictions in a simple case. Here we show that this claim is…

Quantum Physics · Physics 2011-05-09 J. A. Jones , Kiminori Maeda , U. E. Steiner , P. J. Hore

In prior work, we have shown how the basic concepts and terms of quantum mechanics relate to factorizations and marginals of complex-valued quantum mass functions, which are generalizations of joint probability mass functions. In this…

Quantum Physics · Physics 2019-10-08 Hans-Andrea Loeliger , Pascal O. Vontobel

The paper gives a systematic review of the basic ideas of (non-relativistic) quantum mechanics including all changes that result from previous work of the authors. This shows that the new theory is self-consistent and (in certain sense)…

Quantum Physics · Physics 2011-02-24 Petr Hajicek , Jiri Tolar

The quantum measurement problem is revisited and discussed in terms of a new solvable measurement model which basic ingredient is the quantum model of a controlled single-bit memory. The structure of this model involving strongly coupled…

Quantum Physics · Physics 2013-05-22 Robert Alicki

We propose a quantum computation architecture of double-dot molecules, where the qubit is encoded in the molecule two-electron spin states. By arranging the two dots inside each molecule perpendicular to the qubit scaling line, the…

Quantum Physics · Physics 2009-11-13 Hui Zhang , Guo-Ping Guo , Tao Tu , Guang-Can Guo

This work will incorporate a few related tools for addressing the conceptual difficulties arising from sewing together classical and quantum mechanics: deterministic operators, weak measurements and post-selection. Weak Measurement, based…

Quantum Physics · Physics 2016-12-21 Eliahu Cohen , Yakir Aharonov

The multi-stage Stern$\unicode{x2013}$Gerlach experiment conducted by Frisch and Segr\`e includes two cascaded quantum measurements with a nonadiabatic flipper in between. The Frisch and Segr\`e experiment has been modeled analytically by…

Quantum Physics · Physics 2024-08-28 S. Süleyman Kahraman , Kelvin Titimbo , Zhe He , Jung-Tsung Shen , Lihong V. Wang

The implementation of a combination of continuous weak measurement and classical feedback provides a powerful tool for controlling the evolution of quantum systems. In this work, we investigate the potential of this approach from three…

Quantum Gases · Physics 2021-12-17 Jeremy T. Young , Alexey V. Gorshkov , I. B. Spielman

The overlap measurement scheme accomplishes to evaluate the overlap of two input quantum states by only measuring an introduced auxiliary qubit, irrespective of the complexity of the two input states. We find a counterintuitive phenomenon…

Quantum Physics · Physics 2015-06-12 Chang-shui Yu , Jun Zhang , Heng Fan

Quantum superposition is normally sustained in a microscopic regime governed by Heisenberg uncertainty principle applicable to a single particle. Quantum correlation between paired particles implies the violation of local realism governed…

Quantum Physics · Physics 2023-08-21 B. S. Ham

Two of the most common interpretations of quantum measurement disagree about the fate of quantum amplitudes after measurement, yet this disagreement has not previously led to experimentally distinguishable predictions. In the standard…

Quantum Physics · Physics 2026-03-17 Christoph Adami , Lambert Giner , Jeff S. Lundeen , Raphael A. Abrahao

We develop criteria sufficient to enable detection of macroscopic coherence where there are not just two macroscopically distinct outcomes for a pointer measurement, but rather a spread of outcomes over a macroscopic range. The criteria…

Quantum Physics · Physics 2007-05-23 E. G. Cavalcanti , M. D. Reid

Quantum metrology promises measurement precision beyond the classical limit by using suitably tailored quantum states and detection strategies. However, scaling up this advantage is experimentally challenging, due to the difficulty of…

We study dynamics of the measurement process in quantum dot systems, where a particular state out of coherent superposition is observed. The ballistic point-contact placed near one of the dots is taken as a noninvasive detector. We…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 S. A. Gurvitz