Macroscopic ensembles of radiating dipoles are ubiquitous in the physical and natural sciences. In the classical limit the dipoles can be described as damped-driven oscillators, which are able to spontaneously synchronize and collectively lock their phases in the presence of nonlinear coupling. Here we investigate the corresponding phenomenon with arrays of quantized two-level systems coupled via long-range and anisotropic dipolar interactions. Our calculations demonstrate that by incoherently driving dense packed arrays of strongly interacting dipoles, the dipoles can overcome the decoherence induced by quantum fluctuations and inhomogeneous coupling and reach a synchronized steady-state characterized by a macroscopic phase coherence. This steady-state bears much similarity to that observed in classical systems, and yet also exhibits genuine quantum properties such as quantum correlations and quantum phase diffusion (reminiscent of lasing). Our predictions could be relevant for the development of better atomic clocks and a variety of noise tolerant quantum devices.

https://iopscience.iop.org/article/10.1088/1367-2630/17/8/083063/pdf

Synchronization of interacting quantum dipoles

By solving the density matrix equations of a quantum system and taking into account the multibeam interference characteristics of a Fabry-Perot cavity, the output power density of an optically pumped NH/sub 3/ far-infrared (FIR) cavity laser was calculated by means of the iteration method. Based on the calculations, the spectral characteristics and operating parameters of the laser were studied. Experimentally, by using inductive metallic meshes as reflectors and couplers, a series of FIR cavity lasers with a sample tube of 10, 20, and 100 cm in length were designed and constructed, and the emissions of the NH/sub 3/ cavity lasers pumped by a TEA-CO/sub 2/ laser with a 10R(8) or 9R(16) line were measured. The experimental results were in good agreement with theoretical calculations.

Study on spectral characteristics and operating parameters of optically pumped NH/sub 3/ FIR cavity laser

Macroscopic ensembles of radiating dipoles are ubiquitous in the physical and natural sciences. In the classical limit the dipoles can be described as damped-driven oscillators, which are able to spontaneously synchronize and collectively lock their phases. Here we investigate the correspond- ing phenomenon in the quantum regime with arrays of quantized two-level systems coupled via long-range and anisotropic dipolar interactions. Our calculations demonstrate that the dipoles may overcome the decoherence induced by quantum fluctuations and inhomogeneous couplings and evolve to a synchronized steady-state. This steady-state bears much similarity to that observed in classical systems, and yet also exhibits genuine quantum properties such as quantum correlations and quan- tum phase diffusion (reminiscent of lasing). Our predictions could be relevant for the development of better atomic clocks and a variety of noise tolerant quantum devices.

Synchronization of Interacting Quantum Dipoles

The optimum operating parameters of miniature OPFIRL was studied theoretically and experimentally. The theoretical results were in pretty good agreement with experimental results except for 1.5cm laser. The transverse feedback effect plays an important role in the miniature OPFIRL. it's worthv to be funther studied.

Optimum operating parameters of miniature OPFIRL

Gas mixtures CW gain characteristics at 337 mu as function of pressure, current, mixture and flow rate, considering HCN laser systems

The CW gain characteristics of several gas mixtures at 337 microns.

A very short OPFIR superradiant laser was studied theoretically and experimentally. The density matrix equations of a three-level quantum system for NH3 gas was solved for the gains of the FIR signal and the IR signal in the very short OPFIRL system. The output characteristics of the OPFIR superradiant laser were calculated numercally. A curve showing the relation between the length of the sampe tube of the OFFIRL and the corresponding optimum pressure was obtained. In our experiment, a 10cm OPFIRL and a 5cm OPFIRL were constructed and operated successfully. The output characteristics were meassured and the calculated results were verified.

A very short OPFIR superradiant laser

Tunable properties of optically pumped FIR lasers have been studied on the basis of sixlevel quantum system approach. The signal flow graph method was used to solve the density matrix equations. A set of tuning characteristic curves has been obtained in good agreement with the experimental results for optically pumped HF FIR lasers given by A. de Martino et al.

Theory of tunable FIR laser

The influences on HCN laser frequency by the parameters of the laser have been discussed theoretically and experimentally. The frequency variations of the HCN laser versus discharge current and gas pressure have been measured to be 2.9 kHz/mA and 8.1 kHz/mtorr respectively. The experimental results have been explained theoretically.

Qiu Bingshen

Papers

A very short OPFIR superradiant laser

Theory of tunable FIR laser

Influences on HCN laser frequency by the parameters of the laser