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Wolfgang P. Schleich

Publications and source records attributed to Wolfgang P. Schleich.

78 records · Page 5Linked to original sources

Trapping state restoration in the randomly-driven Jaynes-Cummings model by conditional measurements

We propose a scheme which can effectively restore fixed points in the quantum dynamics of repeated Jaynes-Cummings interactions followed by atomic state measurements, when the interaction times fluctuate randomly. It is based on selection of superposed atomic states whose phase correlations tend to suppress the phase fluctuations of each separate state. One suggested realization involves the convergence of the cavity field distribution to a single Fock state by conditional measurements performed on two-level atoms with fluctuating velocities after they cross the cavity. Another realization involves a trapped ion whose internal-motional state coupling fluctuates randomly. Its motional state is made to converge to a Fock state by conditional measurements of the internal state of the ion.

quant-ph↗

The Fermi accelerator in atom optics

We study the classical and quantum dynamics of a Fermi accelerator realized by an atom bouncing off a modulated atomic mirror. We find that in a window of the modulation amplitude dynamical localization occurs in both position and momentum. A recent experiment [A. Steane, P. Szriftgiser, P. Desbiolles, and J. Dalibard, Phys. Rev. Lett. {\bf 74}, 4972 (1995)] shows that this system can be implemented experimentally.

quant-ph↗

Quantum-Non-Demolition Endoscopic Tomography

We present a new indirect method to measure the quantum state of a single mode of the electromagnetic field in a cavity. Our proposal combines the idea of (endoscopic) probing and that of tomography in the sense that the signal field is coupled via a quantum-non-demolition Hamiltonian to a meter field on which then quantum state tomography is performed using balanced homodyne detection. This technique provides full information about the signal state. We also discuss the influence of the measurement of the meter on the signal field.

quant-ph↗

Stabilization of Deterministically Chaotic Systems by Interference and Quantum Measurements: The Ikeda Map Case

We propose a method which can effectively stabilize fixed points in the classical and quantum dynamics of a phase-sensitive chaotic system with feedback. It is based on feeding back a selected quantum sub-ensemble whose phase and amplitude stabilize the otherwise chaotic dynamics. Although the method is rather general, we apply it to realizations of the inherently chaotic Ikeda map. One suggested realization involves the Mach-Zender interferometer with Kerr nonlinearity. Another realization involves a trapped ion interacting with laser fields.

quant-ph↗

Direct and indirect strategies for phase measurement

Recently, Torgerson and Mandel [Phys. Rev. Lett. 76, 3939 (1996)] have reported a disagreement between two schemes for measuring the phase difference of a pair of optical fields. We analyze these schemes and derive their associated phase-difference probability distributions, including both their strong and weak field limits. Our calculation confirms the main point of Torgerson and Mandel of the non-uniqueness of an operational definition of the phase distribution. We further discuss the role of postselection of data and argue that it cannot meaningfully improve the sensitivity.

quant-ph↗

Fractional Talbot effect in phase space: A compact summation formula

A phase space description of the fractional Talbot effect, occurring in a one-dimensional Fresnel diffraction from a periodic grating, is presented. Using the phase space formalism a compact summation formula for the Wigner function at rational multiples of the Talbot distance is derived. The summation formula shows that the fractional Talbot image in the phase space is generated by a finite sum of spatially displaced Wigner functions of the source field.

physics.optics↗