Los Alamos, NM, USA

Research quantum algorithms under the supervision of Yiğit Subaşı. Evaluate fault-tolerant architecture proposals for determining utility of quantum computer proposals (US2QC).

Redmond (virtual), WA, USA

Found algorithms for compilation surface code compilation gate set, with provable speed-ups and lower bounds. Implemented proof of concept in Julia language that shows a 5x speed-up over state-of-the-art. Work performed with Vadym Kliuchnikov, Alexander Vaschillo, and Dmitry Vasilevsky.

Yorktown Heights, NY, USA

Researched algorithms for quantum chemistry and contributed to Qiskit development under the supervision of Ali Javadi-Abhari.

Amsterdam, The Netherlands

Developed and deployed 7 APIs in 3 months using Node.js, RethinkDB and ElasticSearch. Provided interactive website interface and documentation for the APIs using OpenAPI.

Delft, The Netherlands

Worked with Stephanie Wehner to publish my thesis work as paper. Programmed and performed simulations in Scala on a multi-core server. Simulations code: https://github.com/eddieschoute/spherical-routing

Amsterdam, The Netherlands

Constructed a recommender system for arts tourism in the Netherlands using a semantic database.

Delft, The Netherlands

- Assisted and graded one year of masters students in the fourth year Advanced Algorithms course.
- Assisted and graded two years of bachelors students in the second year Algorithms course.

Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, USA

- Researched algorithm for compiling quantum circuits
to respect architecture constraints under supervision of
prof. Andrew Childs. Contributed:
- Algorithmic analysis of swap-based routing and implementation in Python.
- Routing algorithms for Hamiltonian routing.
- Compilation to native gate sets of fault-tolerant architectures and implementation in Julia.

- Co-supervised undergraduate students in NSF research experience for undergraduates (REU): Sam DeCoster, Nicole Dong, and Mason Wittman (2021); Sam King and Hrishee Shahstri (2020).
- Informally co-supervised Cem Unsal for “Circuit Transformations […]” project.
- Worked on quantum algorithms and quantum cryptography under supervision of Yi-Kai Liu.

Delft, The Netherlands

Specialization *Software Technology*, with a
focus on (distributed) algorithms and networks. Master’s
thesis on routing for quantum networks under supervision
of Stephanie Wehner at QuTech.

Delft, The Netherlands

I constructed a proof of concept fiber-optic cable tap for less than €30. I also worked on software acceleration using vectorization (SSE), parallelization (Pthreads, OpenMP), GPGPU programming (CUDA), and DSPs.

Investigate potential problems with current roadways in the county and propose bicycle infrastructure improvements. Research best practices in the US and internationally.

Reviewed abstracts submitted to the Sixth International Conference for Young Quantum Information Scientists conference to ensure a high-quality scientific program targeted to young researchers in quantum information.

As member (2018–2019) and president (2020–2021). Organized and contributed to the annual CS department picnic. Organized student trips and events to foster a community withing the department. Act as liaison between the department and graduate students.

Organized videotaping and processing of QuICS seminars for upload to the QuICS Youtube, to promote accessibility of research.

Assisted with organizing seminar series by organizing food and making healthier options available.

Helped with finding the appropriate hardware and assisted with the live streaming of TQC and NISQ workshop.

A $1000 prize for developing software with IBM’s Qiskit to compile quantum circuits for the IBM quantum computer architectures.

Joint Center for Quantum Information and Computer Science, College Park, MD

Covers tuition, stipend and an additional $5000/yr. Three fellowships were awarded.

University of Maryland, College Park

An award of $2500 yearly.

University of Maryland, College Park

Covers $500 for travel to a conference.

https://www.birs.ca/events/2024/5-day-workshops/24w5307/schedule

US Patent 11,734,596

https://patents.google.com/patent/US11734596B2/en

A method for performing long-range multi-qubit measurements in a quantum circuit utilizes a graph that maps qubits of the quantum circuit to nodes that are connected to one another by edges. The method provides for identifying sets of the nodes on the graph corresponding to sets of qubits targeted by multi-qubit operations in a quantum algorithm and for defining a group of edge-disjoint paths connecting the nodes of each set. The group of edge-disjoint paths is defined such that no two of the paths in the group share an edge. The method further provides for performing a set of operations to entangle the qubits corresponding to the to the identified set of nodes that are included in each path in the group and for performing the set of multi-qubit operations on the entangled sets of the qubits.

US Patent App. 18/178,491

US Patent App. 17/669,946

https://patents.google.com/patent/US20220269966A1/en

Performing state reversal on a quantum spin chain includes: providing qubits in a quantum spin chain in an input state, such that the quantum spin chain includes: first and second terminal qubits and one or more intermediate qubits, such that: the qubits have a transverse field strength; the first and terminal qubits a longitudinal field strength; and nearest neighbor qubit pair has an Ising coupling strength; and evolving the quantum spin chain from the input state to a final state for an evolution period to perform state reversal on the quantum spin chain.

https://arxiv.org/abs/2404.17676

Geometric locality is an important theoretical and practical factor for quantum low-density parity-check (qLDPC) codes which affects code performance and ease of physical realization. For device architectures restricted to 2D local gates, naively implementing the high-rate codes suitable for low-overhead fault-tolerant quantum computing incurs prohibitive overhead. In this work, we present an error correction protocol built on a bilayer architecture that aims to reduce operational overheads when restricted to 2D local gates by measuring some generators less frequently than others. We investigate the family of bivariate bicycle qLDPC codes and show that they are well suited for a parallel syndrome measurement scheme using fast routing with local operations and classical communication (LOCC). Through circuit-level simulations, we find that in some parameter regimes bivariate bicycle codes implemented with this protocol have logical error rates comparable to the surface code while using fewer physical qubits.

https://arxiv.org/abs/2403.18900

Non-Clifford gates are frequently exclusively implemented on fault-tolerant architectures by first distilling magic states in specialised magic-state factories. In the rest of the architecture, the computational space, magic states can then be consumed by a stabilizer circuit to implement non-Clifford operations. We show that the connectivity between the computational space and magic state factories forms a fundamental bottleneck on the rate at which non-Clifford operations can be implemented. We show that the nullity of the magic state, ν(|D⟩) for diagonal gate D, characterizes the non-local resources required to implement D in the computational space. As part of our proof, we construct local stabilizer circuits that use only ν(|D⟩) ebits to implement D in the computational space that may be useful to reduce the non-local resources required to inject non-Clifford gates. Another consequence is that the edge-disjoint path compilation algorithm [PRX Quantum 3, 020342 (2022)] produces minimum-depth circuits for implementing single-qubit diagonal gates.

In: *PRX Quantum*

https://doi.org/10.1103/PRXQuantum.4.010313

The Swap gate is a ubiquitous tool for moving information on quantum hardware, yet it can be considered a classical operation because it does not entangle product states. Genuinely quantum operations could outperform Swap for the task of permuting qubits within an architecture, which we call routing. We consider quantum routing in two models: (1) allowing arbitrary two-qubit unitaries, or (2) allowing Hamiltonians with norm-bounded interactions. We lower bound the circuit depth or time of quantum routing in terms of spectral properties of graphs representing the architecture interaction constraints, and give a generalized upper bound for all simple connected n-vertex graphs. In particular, we give conditions for a superpolynomial classical-quantum routing separation, which exclude graphs with a small spectral gap and graphs of bounded degree. Finally, we provide examples of a quadratic separation between gate-based and Hamiltonian routing models with a constant number of local ancillas per qubit and of an Omega(n) speedup if we also allow fast local interactions.

https://arxiv.org/abs/2204.04185

We study the problem of implementing arbitrary permutations of qubits under interaction constraints in quantum systems that allow for arbitrarily fast local operations and classical communication (LOCC). In particular, we show examples of speedups over swap-based and more general unitary routing methods by distributing entanglement and using LOCC to perform quantum teleportation. We further describe an example of an interaction graph for which teleportation gives a logarithmic speedup in the worst-case routing time over swap-based routing. We also study limits on the speedup afforded by quantum teleportation - showing an O(sqrt(NlogN)) upper bound on the separation in routing time for any interaction graph - and give tighter bounds for some common classes of graphs.

In: *PRX Quantum*

https://doi.org/10.1103/PRXQuantum.3.020342

We provide an efficient algorithm to compile quantum circuits for fault-tolerant execution. We target surface codes, which form a 2D grid of logical qubits with nearest-neighbor logical operations. Embedding an input circuit’s qubits in surface codes can result in long-range two-qubit operations across the grid. We show how to prepare many long-range Bell pairs on qubits connected by edge-disjoint paths of ancillas in constant depth which can be used to perform these long-range operations. This forms one core part of our Edge-Disjoint Paths Compilation (EDPC) algorithm, by easily performing parallel long-range Clifford operations in constant depth. It also allows us to establish a connection between surface code compilation and several well-studied edge-disjoint paths problems. Similar techniques allow us to perform non-Clifford single-qubit rotations far from magic state distillation factories. In this case, we can easily find the maximum set of paths by a max-flow reduction, which forms the other major part of our EDPC algorithm. We compare EDPC to other compilation approaches including a SWAP-based algorithm, and find significantly improved performance for circuits built from parallel CNOTs, and for circuits which implement the multi-controlled X gate.

In: *Quantum*

https://doi.org/10.22331/q-2021-08-31-533

NSF research for undergraduates (REU) work that I co-supervised.

We present methods for implementing arbitrary permutations of qubits under interaction constraints. Our protocols make use of previous methods for rapidly reversing the order of qubits along a path. Given nearest-neighbor interactions on a path of length n, we show that there exists a constant ϵ≈0.034 such that the quantum routing time is at most (1−ϵ)n, whereas any swap-based protocol needs at least time n−1. This represents the first known quantum advantage over swap-based routing methods and also gives improved quantum routing times for realistic architectures such as grids. Furthermore, we show that our algorithm approaches a quantum routing time of 2n/3 in expectation for uniformly random permutations, whereas swap-based protocols require time n asymptotically. Additionally, we consider sparse permutations that route k≤n qubits and give algorithms with quantum routing time at most n/3+O(k2) on paths and at most 2r/3+O(k2) on general graphs with radius r.

In: *Physical Review
Research*

https://doi.org/10.1103/PhysRevResearch.4.L012023

We propose a time-independent Hamiltonian protocol for the reversal of qubit ordering in a chain of N spins. Our protocol has an easily implementable nearest-neighbor, transverse-field Ising model Hamiltonian with time-independent, nonuniform couplings. Under appropriate normalization, we implement this state reversal three times faster than a naive approach using swap gates, in time comparable to a protocol of Raussendorf [Phys. Rev. A 72, 052301 (2005)] that requires dynamical control. We also prove lower bounds on state reversal by using results on the entanglement capacity of Hamiltonians and show that we are within a factor 1.502(1+1/N) of the shortest time possible. Our lower bound holds for all nearest-neighbor qubit protocols with arbitrary finite ancilla spaces and local operations and classical communication. We give numerical evidence that the fast reversal protocols are more robust to noise than a swap-based reversal. Finally, we extend our protocol to an infinite family of nearest-neighbor, time-independent Hamiltonian protocols for state reversal. This includes chains with nearly uniform coupling that may be especially feasible for experimental implementation.

In: *14th Conference on
the Theory of Quantum Computation, Communication and Cryptography (TQC
2019)*

https://www.doi.org/10.4230/LIPIcs.TQC.2019.3

Quantum computer architectures impose restrictions on qubit interactions. We propose efficient circuit transformations that modify a given quantum circuit to fit an architecture, allowing for any initial and final mapping of circuit qubits to architecture qubits. To achieve this, we first consider the qubit movement subproblem and use the routing via matchings framework to prove tighter bounds on parallel routing. In practice, we only need to perform partial permutations, so we generalize routing via matchings to that setting. We give new routing procedures for common architecture graphs and for the generalized hierarchical product of graphs, which produces subgraphs of the Cartesian product. Secondly, for serial routing, we consider the token swapping framework and extend a 4-approximation algorithm for general graphs to support partial permutations. We apply these routing procedures to give several circuit transformations, using various heuristic qubit placement subroutines. We implement these transformations in software and compare their performance for large quantum circuits on grid and modular architectures, identifying strategies that work well in practice.

https://arxiv.org/abs/1610.05238

A quantum network promises to enable long distance quantum communication, and assemble small quantum devices into a large quantum computing cluster. Each network node can thereby be seen as a small few qubit quantum computer. Qubits can be sent over direct physical links connecting nearby quantum nodes, or by means of teleportation over pre-established entanglement amongst distant network nodes. Such pre-shared entanglement effectively forms a shortcut - a virtual quantum link - which can be used exactly once.

Here, we present an abstraction of a quantum network that allows ideas from computer science to be applied to the problem of routing qubits, and manage entanglement in the network. Specifically, we consider a scenario in which each quantum network node can create EPR pairs with its immediate neighbours over a physical connection, and perform entanglement swapping operations in order to create long distance virtual quantum links. We proceed to discuss the features unique to quantum networks, which call for the development of new routing techniques. As an example, we present two simple hierarchical routing schemes for a quantum network of N nodes for a ring and sphere topology. For these topologies we present efficient routing algorithms requiring O(log N) qubits to be stored at each network node, O(polylog N) time and space to perform routing decisions, and O(log N) timesteps to replenish the virtual quantum links in a model of entanglement generation.

http://resolver.tudelft.nl/uuid:684bb201-64a2-461d-b603-1f47590a1341

Master’s thesis.

Bachelor’s thesis.