Stefan Krastanov

Running a group focused on modeling, control, and optimization of quantum computational and networking hardware.

Continuing work in Dirk Englund's group at MIT, leading a number of subprojects and supervising multiple graduate and undergraduate students: quantum control and protocol design for hybrid optical-acoustic-spin hardware, unitary optical neural network hardware, large scale quantum hardware simulation and verification software, and novel classically-efficient entanglement purification methods.

Member of Dirk Englund's group at MIT and Prineha Narang's group at Harvard. Work on photonic architectures for quantum computing with potential for room temperature realizations as well as more general noise mitigation in quantum hardware. Dealing with problems of control, error correction, networking, and algorithm design. Main publications below (see last page for complete list).

• Optically Heralded Entanglement of Superconducting Systems in Quantum Networks, PRL, 2021 a new heralded networking protocol for superconducting transmon devices with unprecedented fidelity compared to typical transduction approaches, applicable to present-day transduction hardware.
• Heterogeneous multipartite entanglement purification for size-constrained quantum devices, PRR, 2021 optimized purification circuits for multi-qubit entangled states, significantly outperforming previous protocols.
• Quantum Coding with Low-Depth Random Circuits, PRX, 2021 a study of quantum error correction codes generated by random (local) circuits.
• Room-Temperature Photonic Logical Qubits via Second-Order Nonlinearities, Nature Communications, 2021 a paradigm for room-temperature photonic quantum logic that significantly simplifies the realization of various quantum circuits, and in particular, of error correction.

Member of Prof. Liang Jiang's group. Work on quantum computing and communication, optimal control, parameter estimation, quantum circuit design, error correction. Main publications below (see last page for complete list).

• Stochastic Estimation of Dynamical Variables, QST, 2019 A stochastic algorithm for the estimation/calibration of Hamiltonians and Lindbladians. Saturates information theory bounds and is resistant to state preparation and measurement errors.
• Optimized Entanglement Purification, Quantum, 2019 Quantum entanglement purification circuits designed by a genetic algorithm, outperforming known circuits in the regime of noisy intermediate scale devices.
• Deep Neural Network Probabilistic Decoder for Stabilizer Codes, Scientific Reports, 2017 A general decoder for small stabilizer codes. First neural net decoder architectures decoding the full stabilizer.
• Universal control of an oscillator with dispersive coupling to a qubit, PRA, 2015 One of the first constructions for efficient and complete unitary control of a transmon/cavity system.

Worked on a symbolic differential geometry module for the Computer Algebra System “SymPy” under the Google Summer of Code: work based on “Functional Differential Geometry” by Wisdom and Sussman, MIT. Other computational work includes Feynman diagrams generator inspired by MadGraph, and work on simulations in cosmology, astrophysics, and molecular dynamics. Experimental projects include Stimulated Brillouin Scattering work in metastable solid Helium during an internship at Laboratoire Kastler Brossel.

Quantum Computing Research, under Prof. Liang Jiang. PhD dissertation defended and submitted. Degree to be awarded in December 2019.

• Autumn 2012 Student exchange at ETH Zürich for one semester as a Master student.
• 2010 - 2013 Integrated Bachelor and Master of Science, Ecole Normale Supérieure de Lyon with the status of a normalien. The ENS Lyon is a highly selective Grande école. Entrance is granted by competitive exams. It trains researchers and teachers in the sciences and the humanities. It's also an active research center.
• 2010 Grandes Écoles competitive exam Admitted at Ecole Polytechnique, Paris and Ecole Normale Supérieure de Lyon.
• 2008 - 2010 Diplôme CPGE, Lycée Louis le Grand, Paris. The Classes Préparatoires aux Grandes Écoles (CPGE) are two very selective years acting as a prep course with the main goal of training students for enrollment in one of the Grandes écoles. The workload is generally very high with focus on Mathematics, Physics and Chemistry. The Grandes écoles are higher education establishments outside the main framework of the French university system. They include science & engineering schools and the three écoles normales supérieures. Due to their competitive entrance exams, they are widely regarded as a prestigious curriculum by students, and traditionally have produced most of France's scientists and executives.

The most flexible and physically realistic quantum network simulator.

One of the fastests and most versatile software tools for working with Quantum Clifford Circuits and Error Correcting Codes through the tableaux method.

Drawing quantum circuits in the Julia language (based on the quantikz latex package).

Faster-than-Clifford simulator and optimizer (through genetic algorithms) of realistically noisy entanglement purification circuits.

I am the author of the differential geometry module for the SymPy computer algebra system. I also authored SymPy's plotting module.

I am a volunteer maintainer for QuantumOptics.jl (state-vector simulator), ResumableFunctions.jl (co-routines engine), ConcurrentSim.jl (discrete event simulator) and other community-run open-source projects.

Numerous simulation tools, including autodifferentiation quantum dynamics solvers in tensorflow, neural network quantum code decoder, and black-box quantization design tools for cQED. Civic service tools including Open Government Data Portals and Virtual Colloquium and Conference Moderation software. An assortment of educational Arduino firmwares.

Design and teach undergraduate and graduate classes in Quantum Information Science, Error Correction, and the Maker subculture.

I run "summer of code" projects and smaller-scale paid open-source bounties, introducing newbie developers and students to the scientific open-source ecosystem. Many of these projects and bounties are funded by independent grants I have secured.

I was the organizer and one of the main instructors at a week-long graduate summer school in numerical methods for quantum information science attended by 45 participants from academia and industry.

One of the lecturers for the introductory course on Machine Learning at MIT, also responsible for the e-learning infrastructure (more than 600 students with heavy use of online tools).

Leading weekly high school classes in preparation for Physics Olympiads.

• Project Based Interdisciplinary Classes In project based learning one teaches the students that they have the skills to actively make the world a better place. I have been a teaching fellow and a consultant for numerous classes that have run at Yale's Center for Engineering Innovation & Design (Yale's academic hacker space), guiding students in redesigning the network of exhibits in one of the Smithsonian museums on the National Mall in Washington; creating sensor networks for smart homes; designing numerous medical devices in collaboration with Yale's Med School; building interactive art and museum installations.
• Traditional Courses and Tutoring Intro Physics, lab and theory; Advanced Physics and Math; Senior level Engineering, Mechatronics; Some Computer Science.

Mentor for two consecutive years at the 2013 and 2014 “Google Summer of Code” programs for the computer algebra system project SymPy.

• Authored for three consecutive years the problems for the Annual Physics Competitions of the Minu Balkanski Foundation and graded the submissions.
• Tutored intensive summer courses for high school physics international competitions at the summer school of Theodisius Teodosiev and at High School of Mathematics and Natural Sciences “acad. N. Obreshkov”, Burgas, Bulgaria.
• Mentor at the Google Code-In high school program for the computer algebra system project SymPy.
• As a high school senior, tutored extracurricular Physics to underclassmen in preparation for Physics competitions.

Together with a colleague at TU Delft, we are developing a hands-on toy, visually representing a whimsical luminous Bloch sphere, employed for educational demonstrations and hands-on experiments. It utilizes a bluetooth connection to fake quantum entanglement in seamless demos.

Joined the organizing committee in 2020, expanding the established RLE's seminar into publicly accessible online series. Created the entirety of the virtual infrastructure for these seminars, now publically available at nonlocalbriefings.com.

Organized seminar to bring scientists together from fields that are seemingly unrelated but are dedicated to the goals of controlling and exploiting quantum systems. Establishing contact between these fields and spark a discussion about topics that we know from our respective perspectives but now introduced in an interdisciplinary light.

A lead designer behind the SpinWheel device, meant to teach Physics and Computer Science through a beautiful programmable wearable trinket. See spinwearables.com.

Design and coordinate outreach activities in mathematical art, physics, engineering, robotics, and electronics for thousands of K12 students. History and current status of the project at engineeringday.com.

Coordinator for GSI, a 200-attendee half-day science outreach event held 4 times a year at the Yale Physics Department.

For my work designing hands-on outreach events. The award recognizes a graduate school student who uses specific knowledge of his/her own discipline as the basis for voluntary service in the local community. Making knowledge and skills from one’s discipline relevant and useful to those in need in the community is the hallmark of this award.

For my work as a teaching fellow for ENG404 "Medical Devices Design and Innovation" under the instruction of Dr. Joseph Zinter. The Prize Teaching Fellowships recognize outstanding performance and promise as a teacher. They are considered among the most important honors that Yale bestows upon graduate students.

Fellowship granted by the Ecole Normale Supérieures on the basis of their competitive entrance exam.

Bronze and Silver medals at the 38th and 39th International Physics Olympiads.

Under the instructions of Martha Lewis, YQI's artist in residence, I contributed much of the electronics behind the "I will be your qubit" art installation for New Haven's Arts and Ideas festival.

In collaboration with colleagues in the School of Engineering, I have prototyped programmable earrings, sensing the motion of the wearer and encoding it in a whimsical pattern of lights.

A persistence of vision laser projector music box, with handcrafted galvanic mirrors, computer vision calibration, and custom vector-to-waveform control software.