Quantum Error Correction of Bosonic Qudits

Quantum Error Correction of Bosonic Qudits
Benjamin Brock, Yale Unviersity
Benjamin Brock
Date and time: Thu, Mar 14, 2024 - 11:30am
Refreshments at 11:15am
Location: LGRT 1033
Category: Condensed Matter Seminar

Hilbert space dimension is a key resource for quantum information processing.  A large Hilbert space is not only an essential requirement for quantum error correction, but it can also be advantageous for realizing gates and algorithms more efficiently.  There has thus been considerable experimental effort in recent years to develop quantum computing platforms using qudits (d-dimensional quantum systems with d>2) as the fundamental unit of quantum information.  Just as with qubits, quantum error correction of these qudits will be necessary for delivering on their promise in the long run, but to date error correction of logical qudits has not been realized experimentally.

In this talk I will present experimental demonstrations of error-corrected qutrits (d=3) and ququarts (d=4) by employing the Gottesman-Kitaev-Preskill (GKP) bosonic code in a circuit QED architecture.  Using a reinforcement learning agent we optimize the GKP qutrit as a ternary quantum memory and demonstrate beyond break-even error correction with a gain of 1.70 ± 0.04.  For the GKP ququart we discover structure to the way physical errors propagate as logical errors, which can be exploited to realize a biased-noise and error-detectable logical qubit embedded in the ququart.  Beyond these particular demonstrations and results, this work opens up many new research directions for quantum information processing with bosonic qudits.


Benjamin Brock is a postdoctoral researcher in Prof. Michel Devoret’s lab at Yale University.  His experimental research focuses on new strategies for bosonic quantum error correction with superconducting circuits.  He received his PhD in Physics from Dartmouth College in 2021 for his work on the cavity-embedded Cooper pair transistor: an ultrasensitive electrometer that can operate at the single-photon level.