TY - THES
AU - Robert Delaney
AB - Entangling superconducting quantum processors via light would enable new means of secure
communication and distributed quantum computing. However, transducing quantum signals between
these disparate regimes of the electromagnetic spectrum remains an outstanding goal and
interfacing superconducting qubits with electro-optic transducers presents signi cant challenges due
to the deleterious effects of optical photons on superconductors. An ideal transducer should leave
the state of the qubit unchanged: more precisely, the backaction from the transducer on the qubit
should be minimal.

In this work, I demonstrate readout of a superconducting transmon qubit via a low-backaction
electro-optomechanical transducer. Requirements for integrating technology from circuit quantum
electrodynamics are discussed, and the results of superconducting qubit readout via an electro-optic
transducer are presented. The modular nature of the transducer and circuit QED system used in
this work enable complete isolation of the superconducting qubit from optical photons, and the
backaction on the qubit from the transducer is less than that imparted by thermal radiation from
the environment. I show that only moderate improvements in transducer bandwidth and added
noise should enable the transduction of non-classical signals from a superconducting qubit to the
optical domain.
BT - Department of Physics
CY - Boulder, CO
DA - 2022-03
N2 - Entangling superconducting quantum processors via light would enable new means of secure
communication and distributed quantum computing. However, transducing quantum signals between
these disparate regimes of the electromagnetic spectrum remains an outstanding goal and
interfacing superconducting qubits with electro-optic transducers presents signi cant challenges due
to the deleterious effects of optical photons on superconductors. An ideal transducer should leave
the state of the qubit unchanged: more precisely, the backaction from the transducer on the qubit
should be minimal.

In this work, I demonstrate readout of a superconducting transmon qubit via a low-backaction
electro-optomechanical transducer. Requirements for integrating technology from circuit quantum
electrodynamics are discussed, and the results of superconducting qubit readout via an electro-optic
transducer are presented. The modular nature of the transducer and circuit QED system used in
this work enable complete isolation of the superconducting qubit from optical photons, and the
backaction on the qubit from the transducer is less than that imparted by thermal radiation from
the environment. I show that only moderate improvements in transducer bandwidth and added
noise should enable the transduction of non-classical signals from a superconducting qubit to the
optical domain.
PB - University of Colorado Boulder
PP - Boulder, CO
PY - 2022
EP - 128
T2 - Department of Physics
TI - Superconducting qubit readout via low-backaction electro-optomechanical transduction
VL - Doctor of Philosophy
ER -