Quantum Brain

Papers

Live trends in quantum computing research, updated daily from arXiv.

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13,354 papers in 12 months (+7% vs prior quarter)

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Papers by research theme (12 months). Hover for details.

Qubit Platforms

Hardware platform mentions in abstractsPhotonic leads

4,120 papers found

Classical variational simulation of the Quantum Approximate Optimization Algorithm

Matija Medvidović, Giuseppe Carleo·Sep 3, 2020

A key open question in quantum computing is whether quantum algorithms can potentially offer a significant advantage over classical algorithms for tasks of practical interest. Understanding the limits of classical computing in simulating quantum syst...

Computer SciencePhysics

Evolutionary Computation for Adaptive Quantum Device Design

Luke Mortimer, M. Estarellas, T. Spiller +1 more·Sep 3, 2020

As noisy intermediate‐scale quantum (NISQ) devices grow in number of qubits, determining good or even adequate parameter configurations for a given application, or for device calibration, becomes a cumbersome task. An evolutionary algorithm is presen...

Computer SciencePhysics

Asymmetry of CNOT gate operation in superconducting transmon quantum processors using cross-resonance entangling

Travis Hurant, D. Stancil·Sep 2, 2020

Controlled-NOT (CNOT) gates are commonly included in the standard gate set of quantum processors and provide an important way to entangle qubits. For fixed-frequency qubits using the cross-resonance entangling technique, using the higher-frequency qu...

Physics

Efficient Encoding of the Weighted MAX $$k$$ k -CUT on a Quantum Computer Using QAOA

F. Fuchs, Herman Oie Kolden, Niels Henrik Aase +1 more·Sep 2, 2020

The weighted MAX $$k$$ k -CUT problem consists of finding a k -partition of a given weighted undirected graph G ( V ,  E ), such that the sum of the weights of the crossing edges is maximized. The problem is of particular interest as it has a multitu...

MathematicsComputer SciencePhysics

Quantum search for scaled hash function preimages

Sergi Ramos-Calderer, E. Bellini, J. Latorre +2 more·Sep 1, 2020

We present the implementation of Grover’s algorithm in a quantum simulator to perform a quantum search for preimages of two scaled hash functions, whose design only uses modular addition, word rotation and bitwise exclusive or. Our implementation pro...

Computer SciencePhysics

A QUBO Formulation for Qubit Allocation

B. Dury, O. D. Matteo·Aug 31, 2020

To run an algorithm on a quantum computer, one must choose an assignment from logical qubits in a circuit to physical qubits on quantum hardware. This task of initial qubit placement, or qubit allocation, is especially important on present-day quantu...

PhysicsComputer Science

Supercomputer simulations of transmon quantum computers

D. Willsch·Aug 31, 2020

We develop a simulator for quantum computers composed of superconducting transmon qubits. The simulation model supports an arbitrary number of transmons and resonators. Quantum gates are implemented by time-dependent pulses. Nontrivial effects such a...

Computer SciencePhysics

Hybrid Quantum-Classical Eigensolver without Variation or Parametric Gates

P. Jouzdani, Stefan Bringuier·Aug 26, 2020

The use of near-term quantum devices that lack quantum error correction, for addressing quantum chemistry and physics problems, requires hybrid quantum-classical algorithms and techniques. Here, we present a process for obtaining the eigenenergy spec...

Physics

Scalable and parallel tweezer gates for quantum computing with long ion strings

Tobias Olsacher, L. Postler, P. Schindler +3 more·Aug 26, 2020

Trapped-ion quantum computers have demonstrated high-performance gate operations in registers of about ten qubits. However, scaling up and parallelizing quantum computations with long one-dimensional (1D) ion strings is an outstanding challenge due t...

Physics

Real- and Imaginary-Time Evolution with Compressed Quantum Circuits

Sheng-Hsuan Lin, R. Dilip, A. Green +2 more·Aug 24, 2020

The current generation of noisy intermediate scale quantum computers introduces new opportunities to study quantum many-body systems. In this paper, we show that quantum circuits can provide a dramatically more efficient representation than current c...

Computer SciencePhysics

Demonstration of quantum volume 64 on a superconducting quantum computing system

P. Jurcevic, Ali Javadi-Abhari, L. Bishop +28 more·Aug 19, 2020

We improve the quality of quantum circuits on superconducting quantum computing systems, as measured by the quantum volume (QV), with a combination of dynamical decoupling, compiler optimizations, shorter two-qubit gates, and excited state promoted r...

PhysicsComputer Science

Bounds on the $\mathrm{QAC}^0$ Complexity of Approximating Parity

G. Rosenthal·Aug 17, 2020

$\mathrm{QAC}$ circuits are quantum circuits with one-qubit gates and Toffoli gates of arbitrary arity. $\mathrm{QAC}^0$ circuits are $\mathrm{QAC}$ circuits of constant depth, and are quantum analogues of $\mathrm{AC}^0$ circuits. We prove the follo...

PhysicsComputer Science

High-Fidelity Controlled-Z Gate with Maximal Intermediate Leakage Operating at the Speed Limit in a Superconducting Quantum Processor.

V. Negîrneac, H. Ali, N. Muthusubramanian +10 more·Aug 17, 2020

Simple tuneup of fast two-qubit gates is essential for the scaling of quantum processors. We introduce the sudden variant (SNZ) of the net zero scheme realizing controlled-Z (CZ) gates by flux control of transmon frequency. SNZ CZ gates realized in a...

MedicinePhysics

Certified quantum gates

W. Campbell·Aug 17, 2020

High quality, fully-programmable quantum processors are available with small numbers (<1000) of qubits, and the scientific potential of these near term machines is not well understood. If the small number of physical qubits precludes practical quantu...

Physics

Quantum advantage for computations with limited space

D. Maslov, Jin-Sung Kim, S. Bravyi +2 more·Aug 14, 2020

Quantum computers promise the ability to solve problems that are intractable in the classical setting1, but in many cases this is not rigorously proven. It is often possible to establish a provable theoretical advantage for quantum computations by re...

Computer SciencePhysics

A simple method for sampling random Clifford operators

E. Berg·Aug 13, 2020

We describe a simple algorithm for sampling $n$-qubit Clifford operators uniformly at random. The algorithm outputs the Clifford operators in the form of quantum circuits with at most $5n + 2n^2$ elementary gates and a maximum depth of $\mathcal{O}(n...

Computer SciencePhysicsMathematics

Single-Photon Image Classification

T. Fischbacher, L. Sbaiz·Aug 13, 2020

Quantum computing-based machine learning mainly focuses on quantum computing hardware that is experimentally challenging to realize due to requiring quantum gates that operate at very low temperature. Instead, we demonstrate the existence of a lower ...

Computer SciencePhysicsMathematics

Improving Hamiltonian encodings with the Gray code

Olivia Di Matteo, A. McCoy, P. Gysbers +3 more·Aug 11, 2020

Due to the limitations of present-day quantum hardware, it is especially critical to design algorithms that make the best possible use of available resources. When simulating quantum many-body systems on a quantum computer, many of the encodings that...

PhysicsComputer Science

Quantum Power Method by a Superposition of Time-Evolved States

K. Seki, S. Yunoki·Aug 9, 2020

We propose a quantum-classical hybrid algorithm of the power method, here dubbed as quantum power method, to evaluate $\hat{\mathcal{H}}^{n}|\psi\rangle$ with quantum computers, where $n$ is a nonnegative integer, $\hat{\mathcal{H}}$ is a time-indepe...

Physics

Faster Schrödinger-style simulation of quantum circuits

Aneeqa Fatima, I. Markov·Aug 1, 2020

Recent demonstrations of superconducting quantum computers by Google and IBM and trapped-ion computers from IonQ fueled new research in quantum algorithms, compilation into quantum circuits, and empirical algorithmics. While online access to quantum ...

Computer SciencePhysics
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