G. Kurizki - Academia.edu (original) (raw)

Papers by G. Kurizki

Proceedings of SPIE - The International Society for Optical Engineering

In this paper, we present a universal control technique, the non-holonomic control, which allows ... more In this paper, we present a universal control technique, the non-holonomic control, which allows us to impose any arbitrarily prescribed unitary evolution to any quantum system through the alternate application of two well-chosen perturbations.

Scientific reports, 2015

We explore means of maximizing the power output of a heat engine based on a periodically-driven q... more We explore means of maximizing the power output of a heat engine based on a periodically-driven quantum system that is constantly coupled to hot and cold baths. It is shown that the maximal power output of such a heat engine whose "working fluid" is a degenerate V-type three-level system is that generated by two independent two-level systems. Hence, level degeneracy is a thermodynamic resource that may effectively double the power output. The efficiency, however, is not affected. We find that coherence is not an essential asset in such multilevel-based heat engines. The existence of two thermalization pathways sharing a common ground state suffices for power enhancement.

International Journal of Modern Physics B, 2005

Coherence and Quantum Optics VI, 1989

Inhibition of spontaneous emission (ISE) has been demonstrated in the past for molecules near a r... more Inhibition of spontaneous emission (ISE) has been demonstrated in the past for molecules near a reflecting surface1 and for Rydberg atoms in microwave cavities.2 In these systems the destructive interference imposed by the boundary conditions on spontaneous emission is sensitive to microscopic changes in the location of the emitter or in the cavity size, as well as to emitters’ polarization.3 Recently, the possibility of obtaining ISE in spectral bands of forbidden light propagation (photonic bandgaps) has been suggested by Yablonovitch.4 These bandgaps are spectral regions admitting only complex wavevectors k (evanescent waves) in any direction, and bounded by frequencies ωmax(min) which the dispersion curve ω(k) becomes discontinuous. Because they are associated with definite k (band edges), such bandgaps are delocalized in space, i.e., they inhibit spontaneous emission independently of the spatial distribution of emitters in the system. The systems that have been proposed4 for the demonstration of bandgaps are dielectric superlattices that exhibit strong three-dimensional (3D) periodic modulations of the dielectric index with a period comparable to half the emission wavelength. The consideration of bandgaps is motivated also by the quest for strong localization of light, i.e., local modes extending over distances of the order of a wavelength. Such modes are predicted by John to occur near the edge of photonic bandgaps in partially disordered structures.5 They can be produced by point or line “defects” altering the strength or periodicity of the dielectric index, or by a “phase slip” in the dielectric superlattice, which is the 3D analog of phase delays introduced into one-dimensional periodic gratings in distributed-feedback lasers.4

NATO Science Series II: Mathematics, Physics and Chemistry

This part gives an overview of recent progress in the area of coherent dynamics and quantum corre... more This part gives an overview of recent progress in the area of coherent dynamics and quantum correlations in systems of mesoscopic and nanoscopic dimensions. On a broad level, the systems considered can be divided in two classes: atomic ensembles and Bose-Einstein condensates (BECs), and superconducting and molecular junctions. Even though these are two different systems that involve different particles (atoms vs. electrons), their basic Hamiltonians are similar, and analogous effects have been observed in both. A striking example hereof is for example the observation of Josephson-like current-phase effects in a trapped atomic condensate [Andrews 1997]. By exploring this multiatom-condensed matter analogy new and interesting insight into the physical properties of both kinds of systems may be gained. Here we are mainly concerned with deviations from the mean field approximation in both types of systems which are related to either quantum correlations and statistics (the papers by Blaauboer et al., O’Dell et al., Katz et al., Ji , and Blaauboer) or

Physica Scripta, 2015

We revisit the thermodynamic bounds of work extraction in simple quantum heat machines subject to... more We revisit the thermodynamic bounds of work extraction in simple quantum heat machines subject to control by frequent modulations that do not comply with adiabatic assumptions. The laws of thermodynamics are obeyed, yet anomalous deviations from the known bounds are revealed.

Physical Review Letters, 1988

... is profoundly modified in molecular, quasimolecular, and excitonic systems hav-ing strong res... more ... is profoundly modified in molecular, quasimolecular, and excitonic systems hav-ing strong resonant optical ... of RDDI suppression on the rate of spontaneous emission via a single mode in the gap is a salient manifestation of field quantization effects on this interaction at all ...

Microcavities and Photonic Bandgaps: Physics and Applications, 1996

We survey our recent results on the modifications of optical processes by field confining structures

Physical Review Letters, 1996

We put forward a theory of excitation decay in two-level atoms that tunnel through a square poten... more We put forward a theory of excitation decay in two-level atoms that tunnel through a square potential barrier while spontaneously emitting photons into an effectively one-dimensional mode continuum. The resulting decoherence can exponentially enhance the total tunneling probability. This enhancement is due to atoms whose final kinetic energy is raised above the barrier by the emission of photons detuned below

Physical Review Letters, 2003

The inversionless free-electron laser having a drift region consisting of two magnets is analyzed... more The inversionless free-electron laser having a drift region consisting of two magnets is analyzed. Performing numerical simulations of electron motion inside wigglers and the drift region, we have shown that this system has a positive mean gain over the entire energy distribution of the electron beam. We study the influence of emittance and the spread of electron energies on the gain.

Chemical Physics Letters, 2006

We present an electrostatic mechanism that gives rise to dramatic enhancements of tunneling throu... more We present an electrostatic mechanism that gives rise to dramatic enhancements of tunneling through the inter-nuclear Coulomb-barrier. The enhancement is due to an increase in the effective negative electric charge in the mid region between two protons (deutrons) belonging to ...

A iinificd theory is given of d.yiamically modilied d e m y and decoherence in driven quantum sys... more A iinificd theory is given of d.yiamically modilied d e m y and decoherence in driven quantum syskms that ;ire coupled to arhitrary finite>-temperature reservoirs a t i d iitidergo random phase fluctuations. Cricoria for the optimization of the suppression and the limitations of this approach are obtained. Decay accelera-6 o n by frequent measuremeiits (interruptions of the coupling), known a s the ant,i-Zeno effect (AZE) is argiied to be much more ubiquitous than it:; inhibit.ioii i n one-or two-level system coupled t,o reservoirs (coritinua). [n multilevel system, frequent niaasuretiients cause acceleTati:d decay by destroying 1.he mult.ilevel interference, which tmds to inhibit decay in tlie ahsence oi measuremer1t.s.

Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel(Dated: Octob... more Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel(Dated: October 26, 2010)We analyze quantum state-transfer optimization within hybrid open systems, from a “noisy”(write-in) qubit to its “quiet” counterpart (storage qubit). Intriguing interplay is revealed betweenour ability to avoid bath-induced errors that profoundly depend on the bath-memory time andthe limitations imposed by leakage out of the operational subspace. Counterintuitively, under nocircumstances is the fastest transfer optimal (for a given transfer energy).

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1984

We present an overview of our comprehensive quanta1 theory of the dynamics of fast charged partic... more We present an overview of our comprehensive quanta1 theory of the dynamics of fast charged particles in crystals and of the radiation they emit. Unlike previous theoretical investigations in this field, ours takes account of the full three-dimensional periodicity of the crystal potential in all dynamical regimes of the particle motion through the crystal. We show that, contrary to prevailing assumptions, the periodicity of the crystal potential, both along the direction of propagation of the particle and transversely to it, give rise to important observable effects and cannot be ignored even for channeled particles. In particular, we show that channeled particles radiate via momentum transfer to the crystal in terms of reciprocal lattice vectors. Thus the spontaneous radiation spectrum predicted by our theory is much richer than what has been known hitherto.

NATO Science Series II: Mathematics, Physics and Chemistry, 2005

We demonstrate that the damping of the motion of an impurity atom injected at a supercritical vel... more We demonstrate that the damping of the motion of an impurity atom injected at a supercritical velocity into a Bose-Einstein condensate can exhibit appreciable deviations from the exponential law on time scales of 10 −5 s.

ISRN Optics, 2013

Due to increasing demands on speed and security of data processing, along with requirements on me... more Due to increasing demands on speed and security of data processing, along with requirements on measurement precision in fundamental research, quantum phenomena are expected to play an increasing role in future technologies. Special attention must hence be paid to omnipresent decoherence effects, which hamper quantumness. Their consequence is always a deviation of the quantum state evolution (error) with respect to the expected unitary evolution if these effects are absent. In operational tasks such as the preparation, transformation, transmission, and detection of quantum states, these effects are detrimental and must be suppressed by strategies known as dynamical decoupling, or the more general dynamical control by modulation developed by us. The underlying dynamics must be Zeno-like, yielding suppressed coupling to the bath. There are, however, tasks which cannot be implemented by unitary evolution, in particular those involving a change of the system’s state entropy. Such tasks n...