本研究基于Dicke模型,探讨了激发态量子相变(ESQPT)对系统非平衡热力学性质的影响。具体来说,通过细致分析量子功分布的性质,深入探究了一阶和二阶激发态量子相变在功分布中体现。我们的结果表明,尽管功分布的特定性质可以很好地刻画Di...本研究基于Dicke模型,探讨了激发态量子相变(ESQPT)对系统非平衡热力学性质的影响。具体来说,通过细致分析量子功分布的性质,深入探究了一阶和二阶激发态量子相变在功分布中体现。我们的结果表明,尽管功分布的特定性质可以很好地刻画Dicke模型中二阶激发态量子相变,但一阶激发态量子相变无法通过功分布得到揭示。该研究一方面表明了功分布在激发态量子相变的研究中具有重要的作用,另一方面也表明了复杂多体模型中激发态量子相变研究的困难性。由于Dicke模型可以在不同的实验平台上得到实现,因而,我们的研究还将进一步促进更多的关于激发态量子相变的实验研究。In this study, by employing the Dicke model, we investigate the impacts of the excited-state quantum phase transitions on the nonequilibrium thermodynamic properties, Specifically, by performing a detailed examination on the features of the quantum work distribution, we investigate how the first- and second-order ESQPTs in the Dicke model manifest themselves in the work distribution. Our results show that the presence of the second-order ESQPT in the Dicke model can be detected by certain properties of the work distribution. However, all our considered features of the work distribution are unable to probe the occurrence of the first-order ESQPT. On the one hand, our findings verify the usefulness of the work distribution in the studies of the ESQPTs. On the other hand, the results of our study also indicate the difficult for analyzing the ESQPTs in complex quantum many-body systems. As the Dicke model can be realized by several experimental platforms, we expect that our studies could motivate more experimental explorations of the signatures of ESQPTs.展开更多
We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of ...We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of the ions to create phonon-mediated entangling gates and,unlike the state of the art,requires neither weakcoupling Lamb-Dicke approximation nor perturbation treatment.With the application of gradient-based optimal control,it enables finding amplitude-and phase-modulated laser control protocols that work without the Lamb-Dicke approximation,promising gate speeds on the order of microseconds comparable to the characteristic trap frequencies.Also,robustness requirements on the temperature of the ions and initial optical phase can be conveniently included to pursue high-quality fast gates against experimental imperfections.Our approach represents a step in speeding up quantum gates to achieve larger quantum circuits for quantum computation and simulation,and thus can find applications in near-future experiments.展开更多
文摘本研究基于Dicke模型,探讨了激发态量子相变(ESQPT)对系统非平衡热力学性质的影响。具体来说,通过细致分析量子功分布的性质,深入探究了一阶和二阶激发态量子相变在功分布中体现。我们的结果表明,尽管功分布的特定性质可以很好地刻画Dicke模型中二阶激发态量子相变,但一阶激发态量子相变无法通过功分布得到揭示。该研究一方面表明了功分布在激发态量子相变的研究中具有重要的作用,另一方面也表明了复杂多体模型中激发态量子相变研究的困难性。由于Dicke模型可以在不同的实验平台上得到实现,因而,我们的研究还将进一步促进更多的关于激发态量子相变的实验研究。In this study, by employing the Dicke model, we investigate the impacts of the excited-state quantum phase transitions on the nonequilibrium thermodynamic properties, Specifically, by performing a detailed examination on the features of the quantum work distribution, we investigate how the first- and second-order ESQPTs in the Dicke model manifest themselves in the work distribution. Our results show that the presence of the second-order ESQPT in the Dicke model can be detected by certain properties of the work distribution. However, all our considered features of the work distribution are unable to probe the occurrence of the first-order ESQPT. On the one hand, our findings verify the usefulness of the work distribution in the studies of the ESQPTs. On the other hand, the results of our study also indicate the difficult for analyzing the ESQPTs in complex quantum many-body systems. As the Dicke model can be realized by several experimental platforms, we expect that our studies could motivate more experimental explorations of the signatures of ESQPTs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12441502,12122506,12204230,and 12404554)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2024ZD0300404)+6 种基金Guangdong Basic and Applied Basic Research Foundation(Grant No.2021B1515020070)Shenzhen Science and Technology Program(Grant No.RCYX20200714114522109)China Postdoctoral Science Foundation(CPSF)(2024M762114)Postdoctoral Fellowship Program of CPSF(GZC20231727)supported by the National Natural Science Foundation of China(Grant Nos.92165206 and 11974330)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301603)the Fundamental Research Funds for the Central Universities。
文摘We present a robust quantum optimal control framework for implementing fast entangling gates on ion-trap quantum processors.The framework leverages tailored laser pulses to drive the multiple vibrational sidebands of the ions to create phonon-mediated entangling gates and,unlike the state of the art,requires neither weakcoupling Lamb-Dicke approximation nor perturbation treatment.With the application of gradient-based optimal control,it enables finding amplitude-and phase-modulated laser control protocols that work without the Lamb-Dicke approximation,promising gate speeds on the order of microseconds comparable to the characteristic trap frequencies.Also,robustness requirements on the temperature of the ions and initial optical phase can be conveniently included to pursue high-quality fast gates against experimental imperfections.Our approach represents a step in speeding up quantum gates to achieve larger quantum circuits for quantum computation and simulation,and thus can find applications in near-future experiments.
