Fall 2020

Quantum error-correction remains a critical component to realizing the full promise of quantum algorithms.  In this talk, I will discuss experimental progress towards creating and controlling logical qubits on a trapped ion quantum computer. Our code of choice is the Bacon-Shor [[9,1,3]] subsystem code, which consists of 9 data qubits, encoding 1 logical qubit, with stabilizer measurements mapped to 4 ancilla qubits capable of correcting any single qubit error.

Looking for some fresh bathroom tiles? Why don't you try regular 7-gons this time, it looks amazing! Only requirement: You'd need to live in hyperbolic space of constant negative curvature. To see how this would be like, let me take you onto a journey into hyperbolic space through recent breakthrough experiments in circuit quantum electrodynamics, where such tilings are realized with superconducting resonators and photons are tricked into believing that space is hyperbolic.

Abstract: Trapped ions are among the most promising candidates for quantum information processors based on their unique properties such as long coherence time, high fidelity state initialization, manipulation and detection. In order to scale up quantum information processors based on trapped ions, efficient sympathetic cooling between different atomic species is required. In this work, we investigate both numerically and experimentally linear harmonic trap parameters to efficiently doppler-cool radial modes of mixed-species Ba-Yb ion chain [1].

We develop approximations to a perturbed quantum dynamics beyond the standard approximation based on quantum Zeno dynamics and adiabatic elimination. The effective generators describing the approximate evolutions are endowed with the same block structure as the unperturbed part of the generator, and their adiabatic error is “eternal” - it does not accumulate over time. We show how this gives rise to Schrieffer-Wolff generators in open systems.

This talk will introduce generalized Jordan–Wigner transformation on arbitrary triangulation of any simply connected manifold in 2d, 3d and general dimensions. This gives a duality between all fermionic systems and a new class of lattice gauge theories. This map preserves the locality and has an explicit dependence on the second Stiefel–Whitney class and a choice of spin structure on the manifold.

Applying a periodic Hamiltonian to a system of particles allows us to study out-of-equilibrium matter, like the prethermal discrete time crystal (PDTC). One can define a time-independent Hamiltonian that describes the dynamics of the driven system not continuously, but in a stroboscopic manner. This implies energy conservation during the validity window of this approximation.

In this work we explore the energy spectrum of a superconducting circuit consisting of a single fluxonium atom coupled to a long section of 1-D transmission line. Owing to the strong anharmonicity of the fluxonium we uncover a new many-body effect, dressing of photons by photons. Specifically, fluxonium's local non-linearity leads to hybridization between one-photon states and nearly resonant multi-photon states.  Accounting for this effect requires deriving the correct multi-mode light matter coupling model of our circuit.

Caroline Figgatt is an atomic physicist working to develop ion trap quantum computers at Honeywell Quantum Systems. She completed her PhD in physics at the University of Maryland in 2018, where she built a programmable ion trap quantum computer and demonstrated a variety of quantum algorithms on it. For her dissertation, she performed the first parallel 2-qubit operations in a single chain of trapped ion qubits. She will talk about quantum research at the company, highlight what it's like to work at Honeywell, and hold a Q&A.

Matrix syntax is a formal model of syntactic relations, based on a conservative and a radical assumption. The conservative assumption dates back to antiquity: that the fundamental divide in human language is between nouns and verbs, which are “conceptually at right angles” (as different as substantive words can be). The radical assumption is that such a conceptual orthogonality could be treated as a formal orthogonality in a vector space, with all its consequences.

It is known that the AdS/CFT correspondence is related to approximate quantum error correction codes. However, the exact manner in which gravity can arise in such codes remains largely unexplored. Here we construct an approximate quantum error correction code which can be represented as a holographic tensor network. In the "noiseless" limit, it admits a local log-depth decoding circuit and reproduces certain properties of holography, such as the Ryu-Takayanagi formula and subregion duality, much like other known holographic codes.