We discuss quantum fluctuation in excited states （named thermo number states） of mesoscopic LC circuits at a finite temperature. By introducing the coherent thermo state into the thermo field dynamics pioneered by U...We discuss quantum fluctuation in excited states （named thermo number states） of mesoscopic LC circuits at a finite temperature. By introducing the coherent thermo state into the thermo field dynamics pioneered by Umezawa and using the natural representation of thermo squeezing operator we can concisely derive the fluctuation. The result shows that the noise becomes larger when either temperature or the excitation number increases.展开更多
Due to the lack of information of subsurface lunar regolith stratification which varies along depth,the drilling device may encounter lunar soil and lunar rock randomly in the drilling process.To meet the load safety ...Due to the lack of information of subsurface lunar regolith stratification which varies along depth,the drilling device may encounter lunar soil and lunar rock randomly in the drilling process.To meet the load safety requirements of unmanned sampling mission under limited orbital resources,the control strategy of autonomous drilling should adapt to the indeterminable lunar environments.Based on the analysis of two types of typical drilling media(i.e.,lunar soil and lunar rock),this paper proposes a multi-state control strategy for autonomous lunar drilling.To represent the working circumstances in the lunar subsurface and reduce the complexity of the control algo-rithm,lunar drilling process was categorized into three drilling states:the interface detection,initi-ation of drilling parameters for recognition and drilling medium recognition.Support vector machine(SVM)and continuous wavelet transform were employed for the online recognition of drilling media and interface,respectively.Finite state machine was utilized to control the transition among different drilling states.To verify the effectiveness of the multi-state control strategy,drilling experiments were implemented with multi-layered drilling media constructed by lunar soil simulant and lunar rock simulant.The results reveal that the multi-state control method is capable of detecting drilling state variation and adjusting drilling parameters timely under vibration interferences.The multi-state control method provides a feasible reference for the control of extraterrestrial autonomous drilling.展开更多
An exact quantum treatment reveals that signal and idler photon number operators are not well-behaved dynamical operators for studying photon statistics in parametric amplification/down-conversion processes. Contrary ...An exact quantum treatment reveals that signal and idler photon number operators are not well-behaved dynamical operators for studying photon statistics in parametric amplification/down-conversion processes. Contrary to expectations, the mean signal-idler photon number difference varies with time, while the corresponding signal-idler photon number cross-correlation function is complex and experiences an interference phenomenon driven by the interaction parameters. The intensity operators and related polarization operators of the polarized signal-idler photon pair in positive and negative helicity states are identified as the appropriate operators specifying a conservation law and the dynamical symmetry group (SU(1, 1)) of the parametric amplification process. The conservation of the mean positive and negative helicity photon intensity difference and the purely real positive-negative helicity intensity cross-correlation function correctly account for the simultaneous production of polarized signal and idler photons in positive and negative helicity states.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10574060 and 10775097)the Natural Science Foundation of Shandong Province of China (Grant No. Y2008A23)the Shandong Province Higher Educational Science and Technology Program (Grant No. J09LA07)
文摘We discuss quantum fluctuation in excited states （named thermo number states） of mesoscopic LC circuits at a finite temperature. By introducing the coherent thermo state into the thermo field dynamics pioneered by Umezawa and using the natural representation of thermo squeezing operator we can concisely derive the fluctuation. The result shows that the noise becomes larger when either temperature or the excitation number increases.
基金financially supported by fundamental research funds for National Natural Science Foundation of China(No.61403106)the Fundamental Research Funds for the Central Universities(No.HIT.NSRIF.2014051)+2 种基金the Program of Introducing Talents of Discipline to Universities(No.B07018)Heilongjiang Postdoctoral Grant(No.LBHZ11168)China Postdoctoral Science Foundation(No.2012M520722)
文摘Due to the lack of information of subsurface lunar regolith stratification which varies along depth,the drilling device may encounter lunar soil and lunar rock randomly in the drilling process.To meet the load safety requirements of unmanned sampling mission under limited orbital resources,the control strategy of autonomous drilling should adapt to the indeterminable lunar environments.Based on the analysis of two types of typical drilling media(i.e.,lunar soil and lunar rock),this paper proposes a multi-state control strategy for autonomous lunar drilling.To represent the working circumstances in the lunar subsurface and reduce the complexity of the control algo-rithm,lunar drilling process was categorized into three drilling states:the interface detection,initi-ation of drilling parameters for recognition and drilling medium recognition.Support vector machine(SVM)and continuous wavelet transform were employed for the online recognition of drilling media and interface,respectively.Finite state machine was utilized to control the transition among different drilling states.To verify the effectiveness of the multi-state control strategy,drilling experiments were implemented with multi-layered drilling media constructed by lunar soil simulant and lunar rock simulant.The results reveal that the multi-state control method is capable of detecting drilling state variation and adjusting drilling parameters timely under vibration interferences.The multi-state control method provides a feasible reference for the control of extraterrestrial autonomous drilling.
文摘An exact quantum treatment reveals that signal and idler photon number operators are not well-behaved dynamical operators for studying photon statistics in parametric amplification/down-conversion processes. Contrary to expectations, the mean signal-idler photon number difference varies with time, while the corresponding signal-idler photon number cross-correlation function is complex and experiences an interference phenomenon driven by the interaction parameters. The intensity operators and related polarization operators of the polarized signal-idler photon pair in positive and negative helicity states are identified as the appropriate operators specifying a conservation law and the dynamical symmetry group (SU(1, 1)) of the parametric amplification process. The conservation of the mean positive and negative helicity photon intensity difference and the purely real positive-negative helicity intensity cross-correlation function correctly account for the simultaneous production of polarized signal and idler photons in positive and negative helicity states.
