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Physics Seminar

Piezoelectric platforms for microwave to optical signal transduction: RF-MEMS meets integrated photonics

Speaker: Krishna Balram (University of Bristol)
Date: Wednesday 23 March 2022
Time: 15:00
Venue: N/3.28

Piezoelectric optomechanical platforms [1] represent one of the most promising routes towards achieving quantum transduction of photons between the microwave and optical frequency domains, with a view towards building distributed (hybrid) quantum networks, around superconducting qubits. However, there are significant challenges to achieving near-unity transduction efficiency in these devices, especially in cryogenic environments. In this talk, I will outline some of these challenges and our work in trying to address them on two complementary fronts: building transducers around a MEMS based high overtone bulk acoustic wave resonator (HBAR) platform [2,3] and engineering transducers in a novel suspended III-V (GaAs) photonic integrated circuits platform [4,5].

[1] Krishna C. Balram, and Kartik Srinivasan. Piezoelectric Optomechanical Approaches for Efficient Quantum Microwave‐to‐Optical Signal Transduction: The Need for Co‐Design. Advanced Quantum Technologies (2021): 2100095.
[2] Stefano Valle and Krishna C. Balram. High-frequency, resonant acousto-optic modulators fabricated in a MEMS foundry platform. Optics Letters 44, no. 15 (2019): 3777-3780.
[3] Stefano Valle and Krishna C. Balram. Cryogenic operation of MEMS-based suspended high overtone bulk acoustic wave resonators for microwave to optical signal transduction. arXiv:2109.11838 (2021).
[4] Pisu Jiang and Krishna C. Balram. Suspended gallium arsenide platform for building large scale photonic integrated circuits: passive devices. Optics Express 28, no. 8 (2020): 12262-12271.
[5] Krishna C. Balram, Marcelo I. Davanço, Jin Dong Song, and Kartik Srinivasan. Coherent coupling between radiofrequency, optical and acoustic waves in piezo-optomechanical circuits. Nature photonics 10, no. 5 (2016): 346-352.

Short Bio: Krishna C. Balram is currently an Associate Professor in Electrical & Electronic Engineering at the University of Bristol. He received his PhD at Stanford University working with David A.B. Miller and was a postdoctoral fellow at the National Institute of Standards & Technology with Kartik Srinivasan. His primary research interest is the development of novel nanofabricated device platforms at the intersection of RF-MEMS and integrated photonics, for manipulating light and sound waves at the nanoscale and engineering controlled interactions between them, and other solid state systems (single spins and nanomagnets). His work is currently supported by an ERC starting grant award.