Balram Group
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Associate Professor Krishna C. Balram
Associate Professor in Photonic Quantum Engineering
Research interests and activities
My 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).
My work pushes the state of the art in nanofabrication methods and, the performance of devices and systems enabled by this establishing Bristol as a centre for excellence in nanofabrication. To enable this, my group also develops novel metrology tools that allows us to probe and quantify wave phenomena at the nanoscale. My interest in metrology is a natural outgrowth of spending three very enjoyable years as a postdoctoral fellow, working with Kartik Srinivasan at NIST Gaithersburg. Before that, I was fortunate to work as a PhD student with David Miller at Stanford.
Major research topics
- Piezo-optomechanics
- Quantum microwave to optical transducers
- RF acoustics
- Integrated photonics
- RF and photonic interfaces to Spin Systems
Current postdocs and research fellows
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Dr Joe Smith
Senior Research Associate
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Dr Vivek Tiwari
Research Associate
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Dr Rob Thomas
Research Associate
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Mahmut Bicer
Research Associate
Current PhD students
- James Cockburn
- Tom Dixon
- Fahad Malik
- Elnaz Shokati
- Jacob Brown
- Haoyang Li
- Zhi Shi
- Cecile Skoryna Kline
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Hao-Cheng (Billy) Weng
(Also with Laing and Matthews groups)
- James Miklaucich
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Fabrication guru
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Pisu Jiang
Senior Process Engineer
Group alumni
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Dr Stefano Valle
Staff MEMS Engineer, SiTime Delft
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Dr Jorge Monroy Ruz
Previous Research Associate
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Dr Ankur Khurana
Previous Research Associate
Active grants
- 2022-25: QC:SCALE , EPSRC ICT standard mode
- 2021-24: GLIMMER, EPSRC ICT standard mode
- 2021-23: SCREAM, EPSRC New Horizons
- 2021-23: GASP, EPSRC Adventurous Manufacturing grant
- 2018-23: SBS3-5 ERC Starting grant
Recent publications
- K.C. Balram and K. Srinivasan, "Piezoelectric Optomechanical Approaches for Efficient Quantum Microwave‐to‐Optical Signal Transduction: The Need for Co‐Design." Advanced Quantum Technologies (2022): 2100095.
- J.A. Smith, C. Clear, K.C. Balram, D.P.S. McCutcheon, and J.G. Rarity, "Nitrogen-Vacancy Center Coupled to an Ultrasmall-Mode-Volume Cavity: A High-Efficiency Source of Indistinguishable Photons at 200 K." Physical Review Applied 15, no. 3 (2021): 034029.
- M. Wu, E. Zeuthen, K.C. Balram, and K. Srinivasan, "Microwave-to-optical transduction using a mechanical supermode for coupling piezoelectric and optomechanical resonators." Physical Review Applied 13, no. 1 (2020): 014027.
- P. Jiang and K.C. Balram, "Suspended gallium arsenide platform for building large scale photonic integrated circuits: passive devices." Optics express 28, no. 8 (2020): 12262-12271.
- J.A. Smith, J. Monroy Ruz, J.G. Rarity, and K.C. Balram, "Single photon emission and single spin coherence of a nitrogen vacancy center encapsulated in silicon nitride." Applied Physics Letters 116, no. 13 (2020): 134001.
- S. Valle, M. Singh, M.J. Cryan, M. Kuball, and K.C. Balram, "High frequency guided mode resonances in mass-loaded, thin film gallium nitride surface acoustic wave devices." Applied Physics Letters 115, no. 21 (2019): 212104.
- S. Valle and K.C. Balram, "High-frequency, resonant acousto-optic modulators fabricated in a MEMS foundry platform." Optics Letters 44, no. 15 (2019): 3777-3780.
Contact me
I am currently looking for PhD students in the general areas of piezoelectric microwave to optical quantum transducers (Wiley AQT 2022) and applying modern RF engineering to develop efficient interfaces to spin systems. If you are interested in these areas, or want to chat about nanofabrication for quantum engineering in general and how it will change the world, please get in touch.