Seminar

(Pizza and refreshments will be served after the talk.)

(Pizza and refreshments will be served after the talk.)

A quantum state that depends on a parameter is a commonly studied structure in quantum physics. Examples include the ground state of a Hamiltonian with a parameter or Bloch states as functions of the quasimomentum. The change in the state as the parameter varies can be characterized by such geometric objects as the Berry phase or the quantum distance which has led to many insights in the understanding of quantum systems.

I will describe a recent quantum algorithm (arXiv:2303.13012) for simulating the classical dynamics of 2^n coupled oscillators (e.g., 2^n masses coupled by springs). The algorithm is based on a mapping between the Schr\"odinger equation and Newton's equations for harmonic potentials such that the amplitudes of the evolved quantum state encode the momenta and displacements of the classical oscillators.

Public verification of quantum money has been one of the central objects in quantum cryptography ever since Wiesner's pioneering idea of using quantum mechanics to construct banknotes against counterfeiting. So far, we do not know any publicly-verifiable quantum money scheme that is provably secure from standard assumptions.

In this talk, we provide both negative and positive results for publicly verifiable quantum money.

Large machine learning models are revolutionary technologies of artificial intelligence whose bottlenecks include huge computational expenses, power, and time used both in the pre-training and fine-tuning process. Based on quantum Carleman linearization and shadow tomography (QRAM is not necessary), we design the first quantum algorithm for training classical sparse neural networks with end-to-end settings.

The steady interest in understanding the thermodynamics of quantum systems has led to several approaches to defining work in a quantum mechanically consistent way (at least almost consistent). The two-point measurement protocol is one such approach that, despite some limitations, has provided a wealth of insight.

In this seminar, I will present and discuss recent results from one of the experimental research lines at Hafezi group: quantum Hall physics in semiconductor microcavities. A 2D charge gas (2DCG) operating in the quantum Hall regime represents one of the few examples of macroscopic quantum behavior. Other examples in this short list are Bose-Einstein condensation and superconductivity. Typically, the experimental study of the quantum Hall effect relies on transport.

Obtaining real-time dynamics of particle collisions is a long-standing goal in high energy and nuclear physics. Developing protocols to simulate lattice gauge theories on quantum simulators offer a strategy to probe these scattering processes. Both long-range and short-range quantum Ising chains exhibit the confinement of quasiparticles, analogous to the high-energy confinement of quarks in bound, meson states. In this talk, we will discuss a proposal to simulate meson scattering in a trapped-ion simulator.