Spontaneous emission

About: Spontaneous emission is a research topic. Over the lifetime, 12855 publications have been published within this topic receiving 323684 citations.

Two-photon interference from a bright single-photon source at telecom wavelengths

Abstract: Long-distance quantum communication relies on the ability to efficiently generate and prepare single photons at telecom wavelengths. In many applications these photons must also be indistinguishable such that they exhibit interference on a beam splitter, which implements effective photon–photon interactions. However, deterministic generation of indistinguishable single photons with high brightness remains a challenging problem. We demonstrate two-photon interference at telecom wavelengths using an InAs/InP quantum dot in a nanophotonic cavity. The cavity enhances the quantum dot emission, resulting in a nearly Gaussian transverse mode profile with high outcoupling efficiency exceeding 36% after multiphoton correction. We also observe a Purcell enhanced spontaneous emission rate of up to 4. Using this source, we generate linearly polarized, high purity single photons at 1.3 μm wavelength and demonstrate the indistinguishable nature of the emission using a two-photon interference measurement, which exhibits indistinguishable visibilities of 18% without postselection and 67% with postselection. Our results provide a promising approach to generate bright, deterministic single photons at telecom wavelength for applications in quantum networking and quantum communication.

1.3-/spl mu/m CW lasing characteristics of self-assembled InGaAs-GaAs quantum dots

Abstract: This paper presents the lasing properties and their temperature dependence for 1.3-/spl mu/m semiconductor lasers involving self-assembled InGaAs-GaAs quantum dots as the active region. High-density 1.3-/spl mu/m emission dots were successfully grown by the combination of low-rate growth and InGaAs-layer overgrowth using molecular beam epitaxy. 1.3-/spl mu/m ground-level CW lasing occurring at a low threshold current of 5.4 mA at 25/spl deg/C with a realistic cavity length of 300 /spl mu/m and high-reflectivity coatings on both facets. The internal loss of the lasers was evaluated to be about 1.2 cm/sup -1/ from the inclination of the plots between the external quantum efficiency and the cavity length. The ground-level modal gain per dot layer was evaluated to be 1.0 cm/sup -1/, which closely agreed with the calculation taking into account the dot density, inhomogeneous broadening, and homogeneous broadening. The characteristic temperature of threshold currents T/sub 0/ was found to depend on cavity length and the number of dot layers in the active region of the lasers. A T/sub 0/ of 82 K was obtained near room temperature, and spontaneous emission intensity as a function of injection current indicated that the nonradiative channel degraded the temperature characteristics. A low-temperature study suggested that an infinite T/sub 0/ with a low threshold current (/spl sim/1 mA) is available if the nonradiative recombination process is eliminated. The investigation in this paper asserted that the improvement in surface density and radiative efficiency of quantum dots is a key to the evolution of 1.3-/spl mu/m quantum-dot lasers.

Stimulated emission and lasing of random-growth oriented ZnO nanowires

Abstract: We report room-temperature ultraviolet stimulated emission and lasing from optically pumped high-quality ZnO nanowires. Emission due to the exciton-exciton scattering process shows apparent stimulated-emission behavior. Several sharp peaks associated with random laser action are seen under high pumping intensity. The mechanism of laser emission is attributed to coherent multiple scattering among the random-growth oriented nanowires. The characteristic cavity length is determined by the Fourier transform of the lasing spectrum.

Spontaneous emission rate alteration in optical waveguide structures

Abstract: Optical microcavities hold technological promise for constructing efficient, high-speed, semiconductor lasers. Achieving the desired effects depends on the degree to which spontaneous emission may be altered by the presence of the cavity. The radiating modes of an oscillating electric dipole placed between two planar metallic mirrors (one-dimensional confinement) and placed in an optical-wire structure (two-dimensional confinement) are discussed. The analysis is carried out using a mode-counting method. The authors show that this method is simpler and more intuitive than traditional classical and quantum electrodynamical calculations. Using the results of the analysis, it is found that an optical wire provides much larger spontaneous-emission-rate alteration than a planar mirror structure. >

Towards Quantum Simulation with Circular Rydberg Atoms

Abstract: The main objective of quantum simulation is an in-depth understanding of many-body physics. It is important for fundamental issues (quantum phase transitions, transport, . . . ) and for the development of innovative materials. Analytic approaches to many-body systems are limited and the huge size of their Hilbert space makes numerical simulations on classical computers intractable. A quantum simulator avoids these limitations by transcribing the system of interest into another, with the same dynamics but with interaction parameters under control and with experimental access to all relevant observables. Quantum simulation of spin systems is being explored with trapped ions, neutral atoms and superconducting devices. We propose here a new paradigm for quantum simulation of spin-1/2 arrays providing unprecedented flexibility and allowing one to explore domains beyond the reach of other platforms. It is based on laser-trapped circular Rydberg atoms. Their long intrinsic lifetimes combined with the inhibition of their microwave spontaneous emission and their low sensitivity to collisions and photoionization make trapping lifetimes in the minute range realistic with state-of-the-art techniques. Ultra-cold defect-free circular atom chains can be prepared by a variant of the evaporative cooling method. This method also leads to the individual detection of arbitrary spin observables. The proposed simulator realizes an XXZ spin-1/2 Hamiltonian with nearest-neighbor couplings ranging from a few to tens of kHz. All the model parameters can be tuned at will, making a large range of simulations accessible. The system evolution can be followed over times in the range of seconds, long enough to be relevant for ground-state adiabatic preparation and for the study of thermalization, disorder or Floquet time crystals. This platform presents unrivaled features for quantum simulation.