Isaac Zheng [Stanford University] & Chao Yin [Stanford University]

Isaac Zheng:

Title: Study of emergent phenomena in graphene systems through transport, capacitance, and microwave techniques

Abstract: Quantum materials host a wide range of emergent phenomena driven by strong correlations and nontrivial topology. Probing these states requires experimental techniques that are directly sensitive to their intrinsic response. In this talk, I will give an overview of my research journey using transport and scanning probe methods to uncover emergent behavior in graphene-based systems, including ferroelectric-like hysteresis, nonlinear Hall effects, and interaction-driven symmetry breaking. Towards the end, I will discuss new directions enabled by advances in microwave quantum sensing: applying scanning SQUID susceptometry to probe two-dimensional superconductors and employing cavity-based techniques to investigate collective modes in heavy-fermion superconductors. Together, these approaches highlight the potential of quantum sensing to reveal the microscopic dynamics of unconventional superconductivity.

Research Interests: quantum dynamics, quantum speed limits, quantum error correction, mathematical physics

Chao Yin

Title: Fast quantum computation using all-to-all Hamiltonians

Abstract: Quantum computation is typically formulated in terms of quantum circuits with all-to-all connectivity, where gates do not overlap. In physical systems, however, it may be more natural to consider all-to-all Hamiltonians, where all pairs of qubits interact simultaneously. Are such Hamiltonians more powerful than circuits with the same interaction strength? In this talk, I will show that the answer is yes: Hamiltonians can process information fundamentally faster. Specifically, I will prove two results. First, certain many-body entangled states, such as the GHZ and W states, can be prepared N-times faster using all-to-all Hamiltonians on N qubits. Second, any quantum circuit can be simulated accurately by Hamiltonians that are faster by a factor of sqrt(N), for almost all input states.

Research interests: quantum dynamics, quantum speed limits, quantum error correction, mathematical physics