The dispersive properties of the atomic transition in rubidium ${D}_{2}$ line ($5{S}_{\frac{1}{2}}\ensuremath{-}5{P}_{\frac{3}{2}}$) at 780.0 nm are measured with a Mach-Zehnder interferometer when an additional coupling field 775.8 is applied to upper ($5{P}_{\frac{3}{2}}\ensuremath{-}5{D}_{\frac{5}{2}}$). This ladder-type system observed exhibit electromagnetically induced transparency together rapidly varying refractive index. A reduction group velocity for probe beam...

This paper presents a review of both active and passive ring laser devices. The operating principles the are developed discussed, with special emphasis given to problems associated achievement greater sensitivity stability. First-principle treatments nature quantum noise in gyro various methods designed avoid low-rotation-rate lock-in presented. Descriptions state-of-the-art devices current proposed applications (including test metric theories gravity using cavity laser) given.

We develop a theory of electromagnetically induced transparency in three-level, ladder-type Doppler-broadened medium, paying special attention to the case where coupling and probe beams are counterpropagating have similar frequencies, so as reduce total Doppler width two-photon process. The is easily generalized deal with \ensuremath{\Lambda} configuration, ideal arrangement involves two copropagating beams. discuss different possible regimes, depending on relative importance various...

The evolution of the atomic state in resonant Jaynes-Cummings model (a two-level atom interacting with a single mode quantized radiation field) field initially coherent is considered. It shown that to good approximation pure middle what has been traditionally called ``collapse region.'' This exhibits no Rabi oscillations and reached independently initial atom. For most states total or partial wave function'' takes place early during interaction, at conventional collapse time, following which...

An asymptotic result is derived for the Jaynes-Cummings model of a two-level atom interacting with quantized single-mode field, which valid when field initially in coherent state large average photon number. It shown that certain initial atomic states joint atom-field wave function factors into an and part throughout interaction, so each system remains separately pure state. The displays crossing trajectories Hilbert space leads to unique atom, independent its state, at specific time...

Recent experiments on quantum behavior in microfabricated solid-state systems suggest tantalizing connections to optics. Several of these address the prototypical problem cavity electrodynamics: a two-level system coupled harmonic oscillator. Such devices may allow exploration parameter regimes outside near-resonance and weak-coupling assumptions ubiquitous rotating-wave approximation (RWA), necessitating other theoretical approaches. One such approach is an adiabatic limit that oscillator...

Two-photon absorption of light with nonclassical (squeezed) fluctuations is considered. Several unique effects are predicted for various possible regimes. These include a linear (instead quadratic) growth the rate intensity weak fields, possibility decreasing increasing intensity, and orders-or-magnitude differences between rates phase- amplitude-squeezed beams same intensity.

An approximate analytical solution is presented, along with numerical calculations, for a system of two single-photon wave packets interacting via an ideal, localized Kerr medium. It shown that, because spontaneous emission into the initially unoccupied temporal modes, cross-phase-modulation in Schr\"odinger picture very small as long spectral width pulses well within medium's bandwidth. In this limit, Hamiltonian used can be derived from ``giant effect'' four-level atom, under conditions...

The transmission spectrum of three-level atoms in a vapor cell inside an optical cavity shows distinct peaks associated with atom-cavity polaritons the system. We develop theory these resonances Doppler-broadened medium and present results experimental observations spectra Lambda-type rubidium ring cavity.

A linear theory of two-photon amplification by three-level atoms in the cascade configuration is developed, where a coherence induced between top and bottom levels, an external classical driving field. It shown that this system becomes ideal parametric amplifier for sufficiently strong field, whereas weak field it phase-insensitive amplifier. In these two extremes, one finds phase-sensitive as well squeezing certain range. The does not, however, reduce to model studied previously atomic was...

The dynamics of a quantum wave packet bouncing on hard surface under the influence gravity are studied. This is system that might be realized experimentally with cold atoms dropped onto an “atomic mirror.” classical limit discussed and interesting departures from behavior pointed out explained.

Abstract The possibility of using squeezed states for improving the shot-noise limit strain sensitivity Michelson interferometers is discussed. We find that spectrum squeezing required depends on method stabilization used in experiment. Details are given widely phase-modulation technique (which also allows recycling field), where we an important application broadband ('two-mode') squeezing.

For a leaky cavity driven by an active medium, we clarify the connection between concepts of single-quasimode squeezing (for intracavity field) and spectral input output fields). Our analysis is based on rigorous construction Fox-Li quasimodes empty superposition true modes perfect, large (infinitely in limit) which fully subsumes cavity. To illustrate physical importance (as defined here as used other authors), consider novel model microscopic system that sensitive to generalized...

We consider a model for quantum battery consisting of collection $N$ two-level atoms driven by classical field and decaying to common reservoir. In the extensive regime, where energy $E$ scales as fluctuations $\mathrm{\ensuremath{\Delta}}E/E\ensuremath{\rightarrow}0$, our dissipative charging protocol yields power proportional ${N}^{2}$, scaling that cannot be achieved in this regime Hamiltonian protocols. The trade-off enhanced is relative inefficiency since large fraction incoming lost...

We discuss the possibility of building a free-electron laser in spectral region tens nanometers using high-power pulse as undulator. Requirements on electron beam emittance, brightness, and energy spread are derived. The operation at quantum limit is considered. reduction gain due to diffraction undulator (the variable mass-shift effect) investigated, several ways which it could be overcome suggested. Examples presented showing that device feasible with moderate advances current injector...

We have investigated the interaction of a single atom with mode radiation field in an ideal cavity when is initially squeezed-vacuum state. In particular, we present results for spectrum emitted light and time evolution squeezing inside cavity. Our contrast sharply previous studies two-level continuum modes. are shown to be insensitive initial phase atomic dipole relative squeezed field, destroyed by coherent interaction, essentially independent degree squeezing. Most features very similar...

It is predicted that a laser's phase-diffusion rate (its Schawlow-Townes linewidth) may be reduced by as much one-half when the laser coupled out to ``squeezed vacuum'' opposed ordinary vacuum. The effect important because it directly related spontaneous emission in squeezed shows part of due amplified zero-point noise and that, therefore, field random phases spontaneously emitted photons are no longer uniformly distributed.

A method is proposed to hide messages in arbitrary quantum data files. The may act as “watermarks,” secure the authenticity and/or integrity of data. With help classical secret keys, they can be made unreadable by other parties and reveal whether thay have been tampered with. basic idea encode using a error-correcting code message (correctible) errors, deliberately inserted, which read out from error syndrome. Also discussed briefly “reverse encoding,” would involve putting actual syndrome,...

A lower bound on the amount of energy needed to carry out an elementary logical operation a quantum computer, with given accuracy and in time, is derived. The arises from requirement that controls used manipulate qubits, which ultimately are themselves quan-tum mechanical systems, must nonetheless be classical sufficiently good approximation; it expected hold under wide variety conditions, independently nature physical systems encode qubits. This could have important consequences for very...

A cross-Kerr interaction produces a phase shift on two modes of light proportional to the number photons in both and is sometimes called cross-phase modulation. Cross-Kerr nonlinearities have many applications classical quantum nonlinear optics, including possibility deterministic all-optical controlled-phase gate. We calculate one- two-photon $S$ matrices for fields propagating medium where spatially distributed at discrete sites comprised atoms. For interactions considered, we analyze...

An approximate solution is given for the Jaynes-Cummings model with cavity losses, i.e., problem of a two-level atom interacting single mode quantized radiation field, in rotating-wave approximation, when field damped by reservoir at zero temperature. The derived initial coherent states moderately large numbers photons. It simpler form than earlier results other authors and, over appropriate parameter range, substantially more accurate some them, as shown direct numerical integration master...

We consider quantum error correction against correlated noise using simple and concatenated Calderbank-Shor-Steane codes as well $n$-qubit repetition codes. characterize the performance of various by means fidelity following a single logical qubit in register. For we find threshold single-qubit rate below which encoded is perfectly protected. The depends on correlation strength goes to zero for perfect correlation. Finally, concatenate traditional correcting with decoherence free subspace...

The quantum nature of the laser fields used in many proposed schemes for manipulation information may have important consequences some very large scale computations. Some these are explored here, focusing especially on phase errors and their effects error-correction schemes. Depending way logical gates performed, constraints found either required number photons per coherence time put out by source, or source's power