Search Results for author: Daniel Liang

Found 7 papers, 1 papers with code

Agnostic Tomography of Stabilizer Product States

no code implementations4 Apr 2024 Sabee Grewal, Vishnu Iyer, William Kretschmer, Daniel Liang

We define a quantum learning task called agnostic tomography, where given copies of an arbitrary state $\rho$ and a class of quantum states $\mathcal{C}$, the goal is to output a succinct description of a state that approximates $\rho$ at least as well as any state in $\mathcal{C}$ (up to some small error $\varepsilon$).

Efficient Learning of Quantum States Prepared With Few Non-Clifford Gates II: Single-Copy Measurements

no code implementations14 Aug 2023 Sabee Grewal, Vishnu Iyer, William Kretschmer, Daniel Liang

Recent work has shown that $n$-qubit quantum states output by circuits with at most $t$ single-qubit non-Clifford gates can be learned to trace distance $\epsilon$ using $\mathsf{poly}(n, 2^t, 1/\epsilon)$ time and samples.

Efficient Learning of Quantum States Prepared With Few Non-Clifford Gates

no code implementations22 May 2023 Sabee Grewal, Vishnu Iyer, William Kretschmer, Daniel Liang

We give a pair of algorithms that efficiently learn a quantum state prepared by Clifford gates and $O(\log n)$ non-Clifford gates.

Low-Stabilizer-Complexity Quantum States Are Not Pseudorandom

no code implementations29 Sep 2022 Sabee Grewal, Vishnu Iyer, William Kretschmer, Daniel Liang

We show that quantum states with "low stabilizer complexity" can be efficiently distinguished from Haar-random.

Clifford Circuits can be Properly PAC Learned if and only if $\textsf{RP}=\textsf{NP}$

no code implementations13 Apr 2022 Daniel Liang

In particular, one candidate class of circuits for which an efficient learner might have been possible was that of Clifford circuits, since the corresponding set of states generated by such circuits, called stabilizer states, are known to be efficiently PAC learnable (Rocchetto 2018).

Computational Efficiency PAC learning

On the Hardness of PAC-learning Stabilizer States with Noise

no code implementations9 Feb 2021 Aravind Gollakota, Daniel Liang

Our results position the problem of learning stabilizer states as a natural quantum analogue of the classical problem of learning parities: easy in the noiseless setting, but seemingly intractable even with simple forms of noise.

Learning Theory PAC learning

Investigating Quantum Approximate Optimization Algorithms under Bang-bang Protocols

1 code implementation27 May 2020 Daniel Liang, Li Li, Stefan Leichenauer

The quantum approximate optimization algorithm (QAOA) is widely seen as a possible usage of noisy intermediate-scale quantum (NISQ) devices.

Quantum Physics

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