Semester Calendar Date

Turbocharging quantum computing through active and passive error suppression

In this talk I will give an overview of various strategies we have developed for suppressing the inevitable errors occurring during quantum computations. These tools work at the gate level and thus can be effective even through a cloud API exposing only elementary gates to the end-user. I will demonstrate the effectiveness of these tools with experimental results across multiple hardware architectures.

The Most Coherent Superconducting Qubit?

To realize a digital quantum processor based on superconducting qubits, gate error rates must be further reduced by raising coherence times and increasing anharmonicity. I report our group's progress in improving coherence and control of fluxonium superconducting qubits by optimizing the circuit's spectrum and enhancing fabrication methods.

Anomalous subdiffusion in quantum chains

Abstract: In typical quantum systems with conservation laws, the approach to equilibrium at finite temperature is governed by classical hydrodynamics in which charge and energy diffuse. In this talk, I will discuss some one dimensional quantum systems with anomalous hydrodynamic behavior — that is, systems where diffusion of charge is replaced by subdiffusion or superdiffusion.

Grand unification of quantum algorithms

Abstract: Modern quantum algorithms originate historically from three disparate origins: simulation, search, and factoring.  Today, we can now understand and appreciate all of these as being instances of a single framework, and remarkably, the essence is how the rotations of a single quantum bit can be transformed non-linearly by a simple sequence of operations.  On the face of it, this is physically non-intuitive, because quantum mechanics is linear.  The key is to think not about eigenvalues and closed systems, but instead, about singular values and subsystem dynamics.

The fine structure of quantum spin ice

Abstract: Quantum spin liquids are low temperature phases of magnetic materials in which quantum fluctuations prevent the establishment of long-range magnetic order. These phases support fractionalized spin excitations (spinons) coupled to emergent photons. In this talk, I will review the basic picture of how quantum electrodynamics emerges in 3D spin ice and then turn to several results regarding its `fine structure'.

All-optical coherent control of solid-state spin qubits toward quantum photonic applications

Abstract: Optically-active spins in the solid-state are useful resources for quantum technologies. The coupling of such systems to photonic structures can generate deterministic spin-photon entanglement, which could contribute to quantum simulations and networking. Ideal spin systems for such applications must combine high quality spin and photonic properties, as well as efficient methods for the coherent manipulation of the spin state.