Daochen Wang
[last initial] [first name] at gmail dot com

I am an assistant professor of computer science at the University of British Columbia, where I research quantum computation and information.

Previously, I obtained my PhD from the University of Maryland under advisors Andrew Childs and Carl Miller. Before that, I obtained my BA and MMath from the University of Cambridge.

Name in Chinese: 王道辰.

Winter Term 2 course page: CPSC 536W.

profile photo

I'm interested in the structures beneath quantum speed-ups, algorithm design, and real-world applications. Recently, I've also become interested in quantum cryptography. Works below are listed in order of first appearance online.

*: equal contribution
: alphabetical order, following convention in TCS

Evaluating the security of CRYSTALS-Dilithium in the quantum random oracle model
Kelsey A. Jackson, Carl A. Miller, Daochen Wang
Eurocrypt 2024 (to appear)

We ground the security of the primary post-quantum digital signature scheme, undergoing standardization by NIST, in the hardness of Module-LWE and Module-SIS.

On the rational degree of Boolean functions and applications
Vishnu Iyer, Siddhartha Jain, Matt Kovacs-Deak, Vinayak M. Kumar, Luke Schaeffer, Daochen Wang, Michael Whitmeyer
arXiv 2023

We prove some special cases of a thirty-year-old conjecture from the analysis of Boolean functions, which has connections to post-selected quantum query complexity.

A theory of quantum differential equation solvers: limitations and fast-forwarding
Dong An, Jin-Peng Liu, Daochen Wang, Qi Zhao
arXiv 2022, in submission

We prove that quantum algorithms generally work best when simulating quantum dynamics but can sometimes be fast-forwarded when simulating non-quantum dynamics.

Lattice-based quantum advantage from rotated measurements
Yusuf Alnawakhtha, Atul Mantri, Carl A. Miller, Daochen Wang
arXiv 2022, in submission

We give a simpler protocol for a quantum computer to prove its quantumness to a classical computer and we explicitly tie the protocol's security to that of LWE.

Quantum divide and conquer
Andrew M. Childs, Robin Kothari, Matt Kovacs-Deak, Aarthi Sundaram, Daochen Wang
arXiv 2022
[QIP 2023] [Waterloo: slides]

We quantumly speed up divide and conquer in certain settings and apply it to string problems, including longest increasing subsequence and longest common subsequence.

Parallel self-testing of EPR pairs under computational assumptions
Honghao Fu, Daochen Wang, Qi Zhao
ICALP 2023

We show how to efficiently self-test the preparation and measurement of multiple EPR pairs assuming LWE cannot be solved quickly by quantum computers. Applications include device-independent quantum key distribution and dimension testing.

Quantum algorithms for reinforcement learning with a generative model
Daochen Wang, Aarthi Sundaram, Robin Kothari, Ashish Kapoor, Martin Roetteler
ICML 2021: slides, talk, poster
[PKU CFCS] [QTML 2021: slides] [QISE-NET: slides]

We quantify the quantum speedups achievable for reinforcement learning in terms of calls to a generative model of the underlying Markov decision process.

Quantum exploration algorithms for multi-armed bandits
Daochen Wang*, Xuchen You*, Tongyang Li, Andrew M. Childs
AAAI 2021: talk
[INFORMS 2021] [GMU: slides] [QTML 2020: slides, talk] [MSR: slides]

We construct an optimal quantum algorithm for identifying the best arm in a multi-armed bandit that is quadratically faster than any classical algorithm.

Symmetries, graph properties, and quantum speedups
Shalev Ben-David, Andrew M. Childs, András Gilyén,
William Kretschmer, Supartha Podder, Daochen Wang
FOCS 2020: short slides, short talk, long talk
[ASQC 2022] [APS 2021: slides] [QIP 2021: talk] [MSR: slides]

We characterise how a problem's symmetries determine whether quantum computation can drastically speed up its solution; it turns out that graph symmetries play the key role.

Subsumes our earlier work [Property Testing Review].

Efficient quantum measurement of Pauli operators
in the presence of finite sampling error

Ophelia Crawford*, Barnaby van Straaten*, Daochen Wang*,
Thomas Parks, Earl Campbell, Stephen Brierley
Quantum 2021
[Q-Turn 2020] [QCTIP 2020: talk]

We reduce the number of measurements needed to estimate the expectation value of an observable by a few orders of magnitude via simultaneous measurements.

Possibilistic simulation of quantum circuits by classical circuits
Daochen Wang
Physical Review A 2022

I extract a notion of "p-simulation" from a breakthrough paper in 2018 and then construct explicit classical circuits that can p-simulate any quantum circuit.

Variational quantum computation of excited states
Oscar Higgott, Daochen Wang, Stephen Brierley
Quantum 2019
[IBM Qiskit] [QCTIP 2019]

We enable the variational quantum eigensolver to compute excited states at little extra cost by penalising overlaps between quantum states.

Accelerated variational quantum eigensolver
Daochen Wang, Oscar Higgott, Stephen Brierley
Physical Review Letters 2019

We accelerate the variational quantum eigensolver by making it behave more like quantum phase estimation as more coherence time becomes available.

Driving Rabi oscillations at the giant dipole resonance in xenon
Stefan Pabst, Daochen Wang, Robin Santra
Physical Review A 2015

We find that super-short yet super-intense pulses of light can drive Rabi oscillations between bound states of negative energy and a pseudo-bound state of positive energy.

OpenFermion: the electronic structure package for quantum computers
Jarrod R. McClean, Kevin J. Sung, Ian D. Kivlichan, Yudong Cao, Chengyu Dai, E. Schuyler Fried, Craig Gidney, Brendan Gimby, Pranav Gokhale, Thomas Häner, Tarini Hardikar, Vojtěch Havlíček, Oscar Higgott, Cupjin Huang, Josh Izaac, Zhang Jiang, Xinle Liu, Sam McArdle, Matthew Neeley, Thomas O'Brien, Bryan O'Gorman, Isil Ozfidan, Maxwell D. Radin, Jhonathan Romero, Nicholas Rubin, Nicolas P. D. Sawaya, Kanav Setia, Sukin Sim, Damian S. Steiger, Mark Steudtner, Qiming Sun, Wei Sun, Daochen Wang, Fang Zhang, Ryan Babbush
Quantum Science and Technology 2020

I contributed code that allows you to automatically retrieve molecular geometries from the PubChem database - try: geometry_from_pubchem('water').

I have worked with great mentors at great companies during my PhD

Pending patents: reinforcement learning with quantum oracle, simultaneous measurement of commuting operators, estimating an energy level of a physical system, a method of determining a state energy.

I was the teaching assistant for the following class

Quantum speedups: structure, design, and application
Daochen Wang

This is my PhD thesis, which I defended in Spring 2023.

Solutions to Theory of Quantum Information
Sandesh Kalantre, Eddie Schoute, Daochen Wang

Solutions to assignment problems from lecture course CS766/QIC820 Theory of Quantum Information (Fall 2017) at Waterloo by John Watrous. These problems also appear in the book on the left.

Past life
The Archimedeans

I used to be president (2014-15) of the Archimedeans, the Cambridge university mathematical society. We held meetings in Michaelmas 2014 and Lent 2015. We also published Eureka 64, click here for an electronic copy. Enjoy!

Last updated: 31st Jan 2024
From Jon Barron