We present a theoretical study of an optical cavity coupled with single four-level atoms in closed loop formed via applied control lasers. The transmitted probe field from the cavity is analyzed. We show that the elec...We present a theoretical study of an optical cavity coupled with single four-level atoms in closed loop formed via applied control lasers. The transmitted probe field from the cavity is analyzed. We show that the electromagnetically induced transparency（EIT） in the cavity and the normal mode splitting will be very different with changing the closed interaction phase and the intensity of the free-space control laser. This coupled cavity-atom system presents a variational double-EIT that comes from modulating the splitting of the dark state, which means that we could realize the gradual transfer between one EIT peak and two EIT peaks by adjusting the applied control lasers, and the normal mode splitting sidebands will shift slightly by changing the free-space control laser. This means that we could control the output cavity probe field more freely and it is easer to realize optical switch controlled by more parameters. We also depict the angular dispersion of the intracavity probe field in different free-space control laser. The large phase shift（-π → π） of the reflected intracavity probe field will be very useful for optical temporal differentiation and quantum phase gate.展开更多
We propose an efficient scheme for optimizing the optical memory of a sequence of signal light pulses in a system of ultracold atoms in ∧ configuration.The memory procedure consists of write-in,storage,and retrieval ...We propose an efficient scheme for optimizing the optical memory of a sequence of signal light pulses in a system of ultracold atoms in ∧ configuration.The memory procedure consists of write-in,storage,and retrieval phases.By applying a weak microwave field in the storage stage,additional phase-dependent terms are included,and the contrast of the output signal pulses can be dynamically controlled（enhanced or suppressed） through manipulating the relative phase φ between optical and microwave fields.Our numerical analysis shows that the contrast is enhanced to the most extent when φ = 1.5π.In addition,the contrast is in proportion to the Rabi frequency of the microwave field with a certain relative phase.展开更多
Temperature,as a measure of thermal motion,is a significant parameter characterizing a cold atomic ensemble optical quantum memory.In a cold gas,storage lifetime strongly depends on its temperature and is associated w...Temperature,as a measure of thermal motion,is a significant parameter characterizing a cold atomic ensemble optical quantum memory.In a cold gas,storage lifetime strongly depends on its temperature and is associated with the spin wave decoherence.Here we experimentally demonstrate a new spin wave thermometry method relying on this direct dependence.The short-wavelength spin waves resulting from the counter-propagating configuration of the control and the probe laser beams make this thermometry highly suitable for probing in situ the atomic motion in elongated clouds as the ones used in quantum memories.Our technique is realized with comparable precision for memories that rely on electromagnetically induced transparency as well as far-detuned Raman storage.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11174109)
文摘We present a theoretical study of an optical cavity coupled with single four-level atoms in closed loop formed via applied control lasers. The transmitted probe field from the cavity is analyzed. We show that the electromagnetically induced transparency（EIT） in the cavity and the normal mode splitting will be very different with changing the closed interaction phase and the intensity of the free-space control laser. This coupled cavity-atom system presents a variational double-EIT that comes from modulating the splitting of the dark state, which means that we could realize the gradual transfer between one EIT peak and two EIT peaks by adjusting the applied control lasers, and the normal mode splitting sidebands will shift slightly by changing the free-space control laser. This means that we could control the output cavity probe field more freely and it is easer to realize optical switch controlled by more parameters. We also depict the angular dispersion of the intracavity probe field in different free-space control laser. The large phase shift（-π → π） of the reflected intracavity probe field will be very useful for optical temporal differentiation and quantum phase gate.
基金Project supported by the National Natural Science Foundation of China(Grant No.11104112)the National Foundation for Fostering Talents of Basic Science,China(Grant No.J1103202)+2 种基金the China Postdoctoral Science Foundation(Grant No.20110491316)the National Undergraduate Innovation Foundation of China(Grant No.2011A32045)the Basic Scientific Research Foundation of Jilin University,China
文摘We propose an efficient scheme for optimizing the optical memory of a sequence of signal light pulses in a system of ultracold atoms in ∧ configuration.The memory procedure consists of write-in,storage,and retrieval phases.By applying a weak microwave field in the storage stage,additional phase-dependent terms are included,and the contrast of the output signal pulses can be dynamically controlled（enhanced or suppressed） through manipulating the relative phase φ between optical and microwave fields.Our numerical analysis shows that the contrast is enhanced to the most extent when φ = 1.5π.In addition,the contrast is in proportion to the Rabi frequency of the microwave field with a certain relative phase.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074171,12074168,92265109,and 12204227)the Key Laboratory Fund from Guangdong Province,China(Grant No.2019B121203002)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2022B1515020096 and 2019ZT08X324).
文摘Temperature,as a measure of thermal motion,is a significant parameter characterizing a cold atomic ensemble optical quantum memory.In a cold gas,storage lifetime strongly depends on its temperature and is associated with the spin wave decoherence.Here we experimentally demonstrate a new spin wave thermometry method relying on this direct dependence.The short-wavelength spin waves resulting from the counter-propagating configuration of the control and the probe laser beams make this thermometry highly suitable for probing in situ the atomic motion in elongated clouds as the ones used in quantum memories.Our technique is realized with comparable precision for memories that rely on electromagnetically induced transparency as well as far-detuned Raman storage.
