We theoretically investigate the quantum phase transition in the collective systems of qubits in a high quality cavity, which is driven by a squeezed light. We show that the squeezed light induced symmetry breaking can result in quantum phase transition without the ultrastrong coupling requirement. Using the standard mean field theory, we derive the condition of the quantum phase transition. Surprisingly, we show that there exist a tricritical point where the first-and second-order phase transitions meet. With specific atom-cavity coupling strengths, both the first-and secondorder phase transition can be controlled by the squeezed light, leading to an optical switching from the normal phase to the superradiant phase by just increasing the squeezed light intensity. The signature of these phase transitions can be observed by detecting the phase space Wigner function distribution with different profiles controlled by the squeezed light intensity. Such superradiant phase transition can be implemented in various quantum systems, including atoms, quantum dots and ions in optical cavities as well as the circuit quantum electrodynamics system.pling cases [18][19][20], where the rotating wave approximation is not valid, the phase transition can also be observed in the undriven Dicke model [17,21,22], but the critical point is displaced when counter-rotating terms are considered [2,23]. It is noted that the normalsuperradiant phase transition are also discovered in the Rabi model [24][25][26], Jaynes-Cummings model [27] and the driven TC system [3, 28-31] by taking the proper thermodynamical limit. Recently, the PT between the symmetric normal state and the state where the NP and SP coexist is proposed in the interpolating Dicke-Tavis-Cummings [17] and Jaynes-Cummings-Rabi [23] models, which opens a new direction in this field.

Mode specificity and product energy disposal are unveiled in the reaction OH + H2S → H2O + SH.

A passive and noninvasive diagnostic system based on high-frequency B-dot probes (HFBs) has been designed and developed for the measurement and identification of ion cyclotron emission (ICE) in the Experimental Advanced Superconducting Tokamak (EAST). Details of the hardware components of this system including HFBs, direct current blockers, radio frequency splitters, filters, and power detectors as well as data acquisition systems are presented. A spectrum analyzer is used in addition to the ordinary speed acquisition card for data registration and analysis. The reliability of a HFB based diagnostic system has been well validated during the 2018 spring experiments on the EAST. ICE signals corresponding to fundamental cyclotron frequency of hydrogen ions and harmonics of deuterium ions were observed in experiments where deuterium plasmas were heated with deuterium neutral beams. The field dependence of ICE has been verified by recent experiments with three different background magnetic fields. The observed ratio of the ICE frequency is consistent with the ratio of the magnetic field intensity within measurement errors of a few percent.