Quantum Simulation of Hawking-Unruh Radiation

Speaker： CongjunWu Time： 10:00am, August 08, 2018 Location： W563, Physics Building Host：杜瑞瑞 [rrd@rice.edu] Abstract: We present recent works on two different aspects of quantum dynamics – symmetry and strong correlations. For the symmetry aspect, we propose a new concept of 'space-time' crystal as a general framework for studying intertwined space-time periodic structures, which include both the static crystal and the Floquet lattice as special cases. A new mathematic structure of 'space-time' group is constructed to describe the symmetries of a space-time crystal, which augments the space group with non-symmorphic operations involving fractional translations along the time domain: 'time-screw rotation' and 'time-glide reflection'. Classifications for the 1+1 D and 2+1D space-time crystals (groups) are completed, and their consequences on dynamic band structures will be discussed. For the strong correlation aspect, we have studied the real frequency response at high energy which is a hard core problem of condensed matter physics. We studied the role of Bethe-string states in the quantum spin dynamics in antiferromagnetic spin chains in high magnetic fields based on algebraic Bethe ansatz via the form-factor formulae. Close to quantum criticality, the string excitations govern the quantum spin dynamics, whereas the fractional excitations, which are dominant at low energies, reflect the antiferromagnetic quantum fluctuations. These states have been recently observed in the electron-spin-resonance spectroscopy measurement on SrCo2V2O8. This work is helpful for experimental studies on spin dynamics in both condensed matter and cold atom systems beyond the low energy effective Luttinger liquid theory. References： S. L. Xu and C. Wu, Phys. Rev. Lett. 120, 096401 (2018) .
W. Yang, J. D. Wu, S. L. Xu, Z. Wang, C. Wu, arXiv:1702.01854.v Z. Wang, J. Wu, W. Yang, A. K. Bera, D. Kamenskyi, A.T.M. N. Islam,
S. Xu, J. M. Law, B. Lake, C. Wu, A. Loidl, Nature 554, 219 (2018).