Can Quantum Measurements Prevent Change?

2020 ◽  
pp. 166-184
Author(s):  
Gershon Kurizki ◽  
Goren Gordon
Keyword(s):  
Quantum State ◽  
High Probability ◽  
Quantum Measurements ◽  
Repeated Measurements ◽  
Quantum Zeno Effect ◽  
Initial State ◽  
Zeno Effect

In a strange dream, Henry is coherently transported towards his bride down the aisle. But just as a small portion of him arrives next to her, that portion disappears in a flash of light caused by a snapshot! Henry keeps trying to be united with his bride, but repeated snapshots cause Henry’s collapse to being far away from her. This dream illustrates the quantum Zeno effect (QZE): if a measurement collapses the quantum state with high probability to the initial state, then frequent repeated measurements can almost stop the change of the quantum state. Yet less frequent measurements cause the opposite, anti-Zeno effect (AZE), whereby change or decay increases. Thus, decay is controllable. These effects confirm Zeno’s argument that change is an illusion, as it is up to the observer to prevent or induce it by appropriate observation. The appendix to this chapter explains the QZE for coherent and decay processes.

scholarly journals Quantum Zeno effect in self-sustaining systems: Suppressing phase diffusion via repeated measurements

2021 ◽  
Vol 103 (4) ◽  
Author(s):  
Wenlin Li ◽  
Najmeh Es'haqi-Sani ◽  
Wen-Zhao Zhang ◽  
David Vitali
Keyword(s):  
Repeated Measurements ◽  
Quantum Zeno Effect ◽  
Phase Diffusion ◽  
Zeno Effect

scholarly journals Optimal polynomial based quantum eigenstate filtering with application to solving quantum linear systems

Quantum ◽  
2020 ◽  
Vol 4 ◽  
pp. 361
Author(s):  
Lin Lin ◽  
Yu Tong
Keyword(s):  
Spectral Gap ◽  
Sparse Matrix ◽  
Query Complexity ◽  
Phase Estimation ◽  
Quantum Zeno Effect ◽  
Initial State ◽  
Zeno Effect ◽  
Optimal Polynomial ◽  
Adiabatic Computing ◽  
Amplitude Amplification

We present a quantum eigenstate filtering algorithm based on quantum signal processing (QSP) and minimax polynomials. The algorithm allows us to efficiently prepare a target eigenstate of a given Hamiltonian, if we have access to an initial state with non-trivial overlap with the target eigenstate and have a reasonable lower bound for the spectral gap. We apply this algorithm to the quantum linear system problem (QLSP), and present two algorithms based on quantum adiabatic computing (AQC) and quantum Zeno effect respectively. Both algorithms prepare the final solution as a pure state, and achieves the near optimal O~(dκlog⁡(1/ϵ)) query complexity for a d-sparse matrix, where κ is the condition number, and ϵ is the desired precision. Neither algorithm uses phase estimation or amplitude amplification.

Theoretical study of Zeno and anti-Zeno effects on photodissociation dynamics: A model approach

2016 ◽  
Vol 15 (08) ◽  
pp. 1650070 ◽  
Author(s):  
Bikram Nath ◽  
Chandan Kumar Mondal
Keyword(s):  
Repeated Measurements ◽  
Time Interval ◽  
Mathematical Tool ◽  
Population Transfer ◽  
Vibrational States ◽  
Initial State ◽  
Zeno Effect ◽  
Dissociation Dynamics ◽  
Vibrational Population

Zeno and anti-Zeno effects in the evolution of the multi-photonic dissociation dynamics of the diatomic molecule HBr[Formula: see text] owing to repeated measurements demand if the system in the initial state have been studied. The effects have been calculated numerically for the case of vibrational population transfer and dissociation dynamics of HBr[Formula: see text] taking it as a model. We use time-dependent Fourier grid Hamiltonian (TDFGH) method as a mathematical tool in presence of intense radiation field as perturbation. The effects have been explored through a probable mechanism of population transfer from the ground vibrational state to the different upper vibrational states which ultimately go to the dissociation continuum. The results show significant differences in the mechanism of population transfer and the significant role of time interval of measurement ([Formula: see text] in Zeno and anti-Zeno effects. In case of survival probability of ground vibrational states, there is Zeno effect when the frequency of the laser to which the molecule is submitted is near the vibrational [Formula: see text] to [Formula: see text] resonance, while there is anti-Zeno effect if it is far from this resonance.

scholarly journals Discrete optical Zeno effect for polarization of light

2021 ◽  
Vol 2086 (1) ◽  
pp. 012167
Author(s):  
K O Sedykh ◽  
D V Sych
Keyword(s):  
Quantum System ◽  
Linear Polarization ◽  
Success Probability ◽  
Quantum Measurements ◽  
Quantum Zeno Effect ◽  
Deterministic Dynamics ◽  
Zeno Effect ◽  
Polarization Of Light

Abstract Quantum Zeno effect concerns deterministic dynamics of a quantum system induced by a series of projective quantum measurements. Applying this effect in optics, one can achieve an arbitrary lossless transformation of linear polarization of light with help of linear polarizers. However, to demonstrate this effect in practice, we have to take into account unavoidable losses in each polarizer that limits probability of successful transformations. In this work, we theoretically study a realistic quantum Zeno effect with an optimal discrete set of polarizers and find the maximum success probability

scholarly journals Evolution of an Atom Impeded by Measurement: The Quantum Zeno Effect

2001 ◽  
Vol 56 (1-2) ◽  
pp. 160-164 ◽  
Author(s):  
Chr. Wunderlich ◽  
Chr. Balzer ◽  
P. E. Toschek
Keyword(s):  
Quantum System ◽  
Quantum State ◽  
Recent Experiment ◽  
Previous Attempt ◽  
Quantum Zeno Effect ◽  
Trapped Ion ◽  
Zeno Effect

Abstract A quantum system being observed evolves more slowly. This "quantum Zeno effect" is reviewed with respect to a previous attempt of demonstration, and to subsequent criticism of the significance of the findings. A recent experiment on an individual cold trapped ion has been capable of revealing the micro-state of this quantum system, such that the effect of measurement is indeed discriminated from dephasing of the quantum state by either the meter or the environment.

scholarly journals Stochastic Process Emerged from Lattice Fermion Systems by Repeated Measurements and Long-Time Limit

Axioms ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 90
Author(s):  
Kazuki Yamaga
Keyword(s):  
Stochastic Process ◽  
Hamiltonian Dynamics ◽  
Repeated Measurements ◽  
Measurement Time ◽  
Initial Time ◽  
Quantum Zeno Effect ◽  
Zeno Effect ◽  
Fermion Systems ◽  
Lattice Fermion ◽  
Long Time

It is known that, in quantum theory, measurements may suppress Hamiltonian dynamics of a system. A famous example is the ‘Quantum Zeno Effect’. This is the phenomena that, if one performs the measurements M times asking whether the system is in the same state as the one at the initial time until the fixed measurement time t, then survival probability tends to 1 by taking the limit M→∞. This is the case for fixed measurement time t. It is known that, if one takes measurement time infinite at appropriate scaling, the ‘Quantum Zeno Effect’ does not occur and the effect of Hamiltonian dynamics emerges. In the present paper, we consider the long time repeated measurements and the dynamics of quantum many body systems in the scaling where the effect of measurements and dynamics are balanced. We show that the stochastic process, called the symmetric simple exclusion process (SSEP), is obtained from the repeated and long time measurements of configuration of particles in finite lattice fermion systems. The emerging stochastic process is independent of potential and interaction of the underlying Hamiltonian of the system.

scholarly journals The quantum Zeno and anti-Zeno effects with driving fields in the weak and strong coupling regimes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mehwish Majeed ◽  
Adam Zaman Chaudhry
Keyword(s):  
Decay Rate ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Repeated Measurements ◽  
Harmonic Oscillators ◽  
Level System ◽  
Quantum Zeno Effect ◽  
Strongly Coupled ◽  
Zeno Effect ◽  
Effective Decay

AbstractRepeated measurements in quantum mechanics can freeze (the quantum Zeno effect) or enhance (the quantum anti-Zeno effect) the time-evolution of a quantum system. In this paper, we present a general treatment of the quantum Zeno and anti-Zeno effects for arbitrary driven open quantum systems, assuming only that the system–environment coupling is weak. In particular, we obtain a general expression for the effective decay rate of a two-level system subjected to arbitrary driving fields as well as periodic measurements. We demonstrate that the driving fields change the decay rate, and hence the quantum Zeno and anti-Zeno behavior, both qualitatively and quantitatively. We also extend our results to systems consisting of more than one two-level system, as well as a two-level system strongly coupled to an environment of harmonic oscillators, to further illustrate the non-trivial effect of the driving fields on the quantum Zeno and anti-Zeno effects.

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