Microwave to Telecom Wavelength Transduction

• Author / Creator

  Ramp, Hugh

• Wavelength transduction of light, specifically between the microwave and telecom regimes, has received a great deal of attention from the cavity optomechanics community as a landmark application for optomechanical systems. Mechanical systems are uniquely suited to wavelength transduction, as photon-phonon momentum transfer allows mechanical motion to couple to light throughout the electromagnetic spectrum. The use of cavities to contain both electromagnetic and mechanical energy in resonators allows for enhanced interaction between light and matter, creating a viable path to high efficiency energy conversion. For a device to act as an ideal transducer, it must satisfy three key parameters: low-noise, high-efficiency, and coherence. In this work we explore gallium arsenide optomechanical crystals as a candidate for microwave-to-telecom wavelength transduction, tackling the basic characteristics of the devices as optomechanicalresonators and profiling their noise and efficiency characteristics.
  To demonstrate transduction efficiency and coherence, we combine the optomechanical crystals with a 3D microwave cavity, and use the piezoelectric properties of gallium arsenide to couple the microwave mode to the gallium arsenide mechanical mode. By injecting a signal into the microwave cavity and measuring it using the gallium arsenide telecom mode, we demonstrate microwave-to-telecom transduction and measure both the efficiency and the coherence of the transducer.
  To demonstrate the low-noise capabilities, we use a dilution refrigerator to cool the optomechanical crystal to a temperature on the order of 10 mK, where we show that the mechanical mode is in the ground state with an average thermal phonon population below one. For the transduction protocol described in this thesis, a ground state mechanical resonator is critical to low-noise transduction, as thermal phonons are transduced in the same way as signal phonons and become added signal at the output of the transducer. We use these low-temperature measurements to estimate the number of added noise photons in a transduced signal. These experiments are the foundation upon which future microwave-to-telecom transduction experiments in the Davis lab will be predicated. The methods described in this thesis, particularly the gigahertz optomechanics measurement techniques and apparatus, will act as a guide to future students who pursue the ultimate goal of transduction: the entanglement of superconducting qubits through a telecom link.

• Subjects / Keywords

  • Microwave
  • Telecom
  • Piezoelectric
  • Optomechanics

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-2bnp-q318

• License

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