Projects

Learn more about some projects I'm working on!

Quantum Emulation (2017- )

The continued success of the digital computing paradigm has been hampered by some of the most fundamental limits of physics. Such considerations have motivated growing interest in unconventional computing approaches based on fundamentally different physical substrates. A simple correspondence of mathematical frameworks between quantum systems and analog electronics spurned the development of quantum emulation, which proposes an equivalent analog electronic representation of a quantum state and provides techniques for transforming such a state in algorithmically useful ways using standard analog electronic components. This helps us understand the limits of processing with classical electronics. My work has included

• designing the firmware and hardware to generate waveforms and process the signals for a prototype device
• developing benchmarks for scalability and noise performance and comparing to candidate noisy intermediate-scale quantum (NISQ) computing systems
• developing novel information extraction methods from such devices using detection theory
• exploring new time and frequency domain methods to encode emulated qubits in analog signals

This work resulted in some publications, including

[1] S.A. Lanham and B.R. La Cour, Detection-Based Measurements for Quantum Emulation Devices. (to appear) in 2020 Inaugural IEEE Quantum Week Conference (QCE20), Denver, CO, USA, 12-16 Oct. 2020

[2] C. Ostrove, B. La Cour, S.A. Lanham, G. Ott, Improving Performance of an Analog Electronic Device Using Quantum Error Correction. J. Phys. Comm. 3, 085017 (2019). https://dx.doi.org/10.1088/2399-6528/ab3c37

[3] B. R. La Cour, S. A. Lanham, C. I. Ostrove, Parallel quantum computing emulation. 2018 IEEE International Conference on Rebooting Computing (ICRC), McLean, VA, USA, 7-9 Nov. 2018. https://ieeexplore.ieee.org/document/8638597

[4] B. R. La Cour, G. E. Ott, and S. A. Lanham, Using quantum emulation for advanced computation. 2017 IEEE Custom Integrated Circuits Conference (CICC), Austin, TX, USA. http://dx.doi.org/10.1109/CICC.2017.7993631

Space-Time Codes From Stabilizer Groups (2018- )

In this project, we have adapted a family quantum error correcting codes into competitive statistical signal processing algorithms for wireless communication. Quantum error correction is a protocol that encodes and preserves information against detrimental noise processes, generally using only statistical information about the noise (as determined by a tomographic process). This situation is similar to one encountered in the wireless communication setting when channel estimates are not available (called noncoherent communication). Leveraging this similarity, we designed a multi-antenna space-time code using stabilizer coding. We showed that stabilizer codes can be used to faithfully recover transmitted symbols in the absence of channel estimates. These codes exhibit full diversity and bit error rates competitive with the Alamouti code.

This work resulted in a publication, with a journal version in preparation

[1] S. A. Lanham, T. C. Cuvelier, C. Ostrove, B. La Cour, G. Ott, R. Heath Jr., A noncoherent space-time code from quantum error correction. 53rd Annual Conference on Information Sciences and Systems (CISS), Johns Hopkins University, 20-22 March 2019. https://ieeexplore.ieee.org/document/8692830 (https://arxiv.org/pdf/1812.07115.pdf)

Using Optimization to Find New Quantum Error Correcting Codes (2019- )

Quantum error correcting codes can be regarded as subspaces satisfying a set of conditions deemed necessary and sufficient to preserve quantum information against corrupting noise processes. Can the problem of designing a good quantum error correcting code be treated as an optimization problem? How efficiently can such problems be solved? A useful insight may be to consider codes as points on a topological space known as the Grassmann manifold, which has received some attention in the theory of optimization.

Designing Efficient Comb Filters Using Symmetry (2019)

The scaling of our quantum emulation device introduced a series of difficult comb filter design problems. If filtering is performed digitally, there are many options, such as FIR and IIR filter banks, and FFT based methods. By observing that in our application, the passband and stopband can be expressed as a recursive odd or even indexed subsequence of the frequency representation of the signal, I designed a very low complexity family of comb filters using an algorithm inspired by the radix-2 decimation in frequency FFT.

Quad Envelope Generator (2016-2017)

I worked for some time as a contract firmware engineer to design an ADSR generator for a modular synthesizer rack. The development was on a Microchip PIC32 series microcontroller. The ADSR generator features linear and exponential families of curves, many unique triggering setups, and four independent channels. The module has various modes which create chaining behavior between the four channels, resulting in intense modular madness!

Texas Music Producers (2015-2017)

I am proud to have co-founded the first student organization dedicated to electronic music production at the University of Texas at Austin, which is still running strong! TMP has offered a platform for established artists to teach masterclasses and workshops for UT students (and other visitors) to flex their creative muscles under the guidance of a staff of talented student instructors. Find us on Twitter or Facebook (@TexasProducers, TexasMusicProducers).