Speaker: Twesh Upadhyaya
I will take this opportunity to share with the Waterloo quantum community the thinkings behind Alibaba Group's quantum computing program and our main activities. Questions and comments from the audience are welcome.
About the speaker: Yaoyun Shi is a computer scientist trained at Beijing University, Princeton, and Caltech. He taught at University of Michigan before moving to Alibaba to launch its quantum computing program.
When a quantum system is monitored with a sequence of measurements, its evolution is given by a stochastic quantum trajectory. At any time the state, and therefore any prediction we can make about an observable, is dependent on previous measurement outcomes. Past quantum state, on the other hand, is a general theory that allows us to include the information collected about the system with later measurements.
The fields of opto- and electromechanics have facilitated numerous advances in the areas of precision measurement and sensing, ultimately driving the studies of mechanical systems into the quantum regime. To date, however, the quantization of the mechanical motion and the associated quantum jumps between phonon states remains elusive. For optomechanical systems, the coupling to the environment was shown to preclude the detection of the mechanical mode occupation, unless strong single photon optomechanical coupling is achieved.
Quantum physics holds the promise of enhanced performance in metrology and sensing by exploiting non-classical phenomena such as multiparticle interference. Specific designs for quantum-enhanced schemes need to take into account noise and imperfections present in real-life implementations.
It has been suggested that placing dipolar linear rotors in one-dimensional lattices at zero temperature results in a model that has a transition between ordered and disordered phases. We use the density matrix renormalization group (DMRG) to compute ground states of this model near the critical point to provide further evidence of the phase transition. In particular, we numerically demonstrate divergences in both the entanglement entropy and the correlation length.
A nonlocal game with a synchronous correlation is the ideal protocol for quantum key distribution. In this work we examine analogues of Bell's inequalities for synchronous correlations. We show that unlike in the nonsynchronous case (e.g. with the CHSH inequality) there can be no quantum Bell violation among synchronous correlations with two measurement settings. However we exhibit explicit analogues of Bell's inequalities for synchronous correlation with three measurement settings and two outputs that do admit quantum violations.
Surface acoustic waves (SAWs) are acoustic phonons that travel along the surface of a material and have been used for a wide variety of purposes, from RF filters to acoustic cavities to biosensors.
Quantum secret sharing (QSS) mainly deals with the splitting and distributing of an arbitrary secret among n sharers using quantum resources. While quantum secret sharing schemes often use shared entangled states, it is also possible to define a notion of quantum secret sharing without the use of entangled states.
A brief history and overview of the requirements to guide the research and development for high-coherence superconducting quantum circuits will be given. The main focus will be on materials development at NIST. Topics will include identifying and mitigating loss due to amorphous two-level systems at interfaces and how to scale the fabrication of small aluminum-oxide tunnel junctions. The junctions were studied with atom probe microscopy to get an understanding of where the oxidation occurs.