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M. Bienert

Publications and source records attributed to M. Bienert.

6 recordsLinked to original sources
arXiv2010

Quantum jumps induced by the center-of-mass motion of a trapped atom

We theoretically study the occurrence of quantum jumps in the resonance fluorescence of a trapped atom. Here, the atom is laser cooled in a configuration of level such that the occurrence of a quantum jump is associated to a change of the vibrational center-of-mass motion by one phonon. The statistics of the occurrence of the dark fluorescence period is studied as a function of the physical parameters and the corresponding features in the spectrum of resonance fluorescence are identified. We discuss the information which can be extracted on the atomic motion from the observation of a quantum jump in the considered setup.

quant-ph↗
arXiv2007

Thermalized non-equilibrated matter and high temperature superconducting state in quantum many-body systems

A characteristic feature of thermalized non-equilibrated matter is that, in spite of energy relaxation--equilibration, a phase memory of the way the many-body system was excited remains. As an example, we analyze data on a strong forward peaking of thermal proton yield in the Bi($γ$,p) photonuclear reaction. New analysis shows that the phase relaxation in highly-excited heavy nuclei can be 8 orders of magnitude or even much longer than the energy relaxation. We argue that thermalized non-equilibrated matter resembles a high temperature superconducting state in quantum many-body systems. We briefly present results on the time-dependent correlation function of the many-particle density fluctuations for such a superconducting state. It should be of interest to experimentally search for manifestations of thermalized non-equilibrated matter in many-body mesoscopic systems and nanostructures.

cond-mat.supr-con↗
arXiv2006

Opacity of electromagnetically induced transparency for quantum fluctuations

We analyze the propagation of a pair of quantized fields inside a medium of three-level atoms in $Λ$ configuration. We calculate the stationary quadrature noise spectrum of the field after propagating through the medium, in the case where the probe field is in a squeezed state and the atoms show electromagnetically induced transparency (EIT). We find an oscillatory transfer of the initial quantum properties between the probe and pump fields which is most strongly pronounced when both fields have comparable Rabi frequencies. This implies that the quantum state measured after propagation can be completely different from the initial state, even though the mean values of the field are unaltered.

quant-ph↗
arXiv2006

Anomalously Slow Cross Symmetry Phase Relaxation, Thermalized Non-Equilibrated Matter and Quantum Computing Beyond the Quantum Chaos Border

Thermalization in highly excited quantum many-body system does not necessarily mean a complete memory loss of the way the system was formed. This effect may pave a way for a quantum computing, with a large number of qubits $n\simeq 100$--1000, far beyond the quantum chaos border. One of the manifestations of such a thermalized non-equilibrated matter is revealed by a strong asymmetry around 90$^\circ $ c.m. of evaporating proton yield in the Bi($γ$,p) photonuclear reaction. The effect is described in terms of anomalously slow cross symmetry phase relaxation in highly excited quantum many-body systems with exponentially large Hilbert space dimensions. In the above reaction this phase relaxation is about eight orders of magnitude slower than energy relaxation (thermalization).

quant-ph↗
arXiv2002

Kicked Rotor in Wigner Phase Space

We develop the Wigner phase space representation of a kicked particle for an arbitrary but periodic kicking potential. We use this formalism to illustrate quantum resonances and anti--resonances.

quant-ph↗