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Photonic and Phononic Band Gap Engineering for Circuit Quantum Electrodynamics and Quantum Transduction


Banker, Jash Haren (2022) Photonic and Phononic Band Gap Engineering for Circuit Quantum Electrodynamics and Quantum Transduction. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/jrf3-gx27.


The ability to pattern materials at the wavelength and sub-wavelength scale has led to the concept of photonic crystals and metamaterials - artificially engineered structures that exhibit electromagnetic properties not found in conventional materials. Such engineered structures offer the ability to slow down and even inhibit the propagation of electromagnetic waves giving rise to a photonic band gap and a sharply varying photonic density of states.

Quantum emitters in the presence of an electromagnetic reservoir with varying density of states can undergo a rich set of dynamical behavior. In particular, the reservoir can be tailored to have a memory of past interactions with emitters, in contrast to memory-less Markovian dynamics of typical open systems. In part 1 of this thesis, we investigate the non-Markovian dynamics of a superconducting qubit strongly coupled to a superconducting metamaterial waveguide engineered to have both a sharp spectral variation in its transmission properties and a slowing of light by a factor of 650. Tuning the qubit into the spectral vicinity of the passband of this slow-light waveguide reservoir, we observe a 400-fold change in the emission rate of the qubit, along with oscillatory energy relaxation of the qubit resulting from the beating of bound and radiative dressed qubit-photon states. Further, upon addition of a reflective boundary to one end of the waveguide, we observe revivals in the qubit population on a timescale 30 times longer than the inverse of the qubit’s emission rate, corresponding to the round-trip travel time of an emitted photon. With this superconducting circuit platform, future studies of multi-qubit interactions via highly structured reservoirs and the generation of multi-photon highly entangled states are possible.

While microwave frequency superconducting circuits are near ideal testbeds for quantum electrodynamics experiments of the type discussed in part 1, microwave photons are not well suited for transmission of quantum information over long distances due to the presence of a large thermal background at room temperature. Optical photons are ideal for quantum communication applications due to their low propagation loss at room temperature. Coherent transduction of single photons from the microwave to the optical domain has the potential to play a key role in quantum networking and distributed quantum computing. In part 2 of this thesis, we extend the notion of band gap engineering to the optical and acoustic domain and present the design of a piezo-optomechanical quantum transducer where transduction is mediated by a strongly hybridized acoustic mode of a lithium niobate piezoacoustic cavity attached to a silicon optomechanical crystal patterned on a silicon-on-insulator substrate. We estimate an intrinsic transduction efficiency of 29% with <0.5 added noise quanta when our transducer is resonantly coupled to a superconducting transmon qubit and operated in pulsed mode. Our design involves on-chip integration of a superconducting qubit with the piezo-optomechanical transducer. Absorption of stray photons from the optical pump used in the transduction process is known to cause excess decoherence and noise in the superconducting circuit. The recovery time of the superconducting circuit after the optical pulse sets a limit on the transducer repetition rate. We fabricate niobium based superconducting circuits on a silicon substrate and test their response to illumination by a 1550 nm laser. We find a recovery time of ~ 10 μs, indicating that a repetition rate of 10 kHz should be possible. Combined with the expected efficiency and noise metrics of our design, we expect that a transducer in this parameter regime would be suitable to realize probabilistic schemes for remote entanglement of superconducting quantum processors. We conclude by discussing some of the challenges associated with fabricating niobium superconducting qubits and lithium niobate piezoacoustic devices on silicon-on-insulator substrates and provide initial steps towards realizing our transducer design in the lab.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Superconducting circuits; piezo-opto-mechanics; non-Markovian physics; quantum transduction
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Painter, Oskar J.
Thesis Committee:
  • Vahala, Kerry J. (chair)
  • Faraon, Andrei
  • Minnich, Austin J.
  • Painter, Oskar J.
Defense Date:20 October 2021
Record Number:CaltechTHESIS:01222022-151042739
Persistent URL:
Related URLs:
URLURL TypeDescription article adapted for chapters 2, 3, and 4.
Banker, Jash Haren0000-0002-2130-0825
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14484
Deposited By: Jash Banker
Deposited On:26 Jan 2022 01:46
Last Modified:08 Nov 2023 18:50

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