Quantum Brain

Papers

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

Total Papers

31,714

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152

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0

Research Volume

15,749 papers in 12 months (-37% vs prior quarter)

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Hardware platform mentions in abstractsPhotonic leads

31,714 papers found

Characterizing the boundary of the set of absolutely separable states and their generation via noisy environments

Saronath Halder, S. Mal, Aditi Sen(De)·Nov 29, 2019

We characterize the boundary of the convex compact set of absolutely separable states, referred as AS, that cannot be transformed to entangled states by global unitary operators, in 2⊗ d Hilbert space. However, we show that the absolutely separable s...

Physics

Quantum computation with machine-learning-controlled quantum stuff

L. Hardy, Adam G. M. Lewis·Nov 29, 2019

We formulate the control over quantum matter, so as to perform arbitrary quantum computation, as an optimization problem. We then provide a schematic machine learning algorithm for its solution. Imagine a long strip of ‘quantum stuff’, endowed with c...

PhysicsComputer Science

Scheduler of quantum circuits based on dynamical pattern improvement and its application to hardware design

G. Guerreschi·Nov 29, 2019

As quantum hardware increases in complexity, successful algorithmic execution relies more heavily on awareness of existing device constraints. In this work we focus on the problem of routing quantum information across the machine to overcome the limi...

Computer SciencePhysics

Entaglement-Based Quantum Mean Estimator Circuit

Amanuel Tamirat·Nov 28, 2019

This paper proposes a quantum circuit for computing the mean value from a given set of quantum states. The circuit consults a Quantum Random Access Memory to get the values of the set, and by using superposition, interference and entanglement phenome...

Physics

Quantum Weakest Preconditions for Reasoning about Expected Runtimes of Quantum Programs

Junyi Liu, Li Zhou, G. Barthe +1 more·Nov 28, 2019

We study expected runtimes for quantum programs. Inspired by recent work on probabilistic programs, we first define expected runtime as a generalisation of quantum weakest precondition. Then, we show that the expected runtime of a quantum program can...

Computer SciencePhysics

Quantum Lower Bounds for 2D-Grid and Dyck Language

A. Ambainis, K. Balodis, Janis Iraids +2 more·Nov 28, 2019

We show quantum lower bounds for two problems. First, we consider the problem of determining if a sequence of parentheses is a properly balanced one (a Dyck word), with a depth of at most $k$. It has been known that, for any $k$, $\tilde{O}(\sqrt{n})...

Computer SciencePhysicsMathematics

An adaptive algorithm for quantum circuit simulation

R. Schutski, Danil Lykov, I. Oseledets·Nov 28, 2019

Efficient simulation of quantum computers is essential for the development and validation of near-term quantum devices and the research on quantum algorithms. Up to date, two main approaches to simulation were in use, based on either full state or si...

Computer SciencePhysics

Reduction of qubits in a quantum algorithm for Monte Carlo simulation by a pseudo-random-number generator

Koichi Miyamoto, Kenji Shiohara·Nov 28, 2019

It is known that quantum computers can speed up Monte Carlo simulation compared to classical counterparts. There are already some proposals of application of the quantum algorithm to practical problems, including quantitative finance. In many problem...

Computer SciencePhysicsEconomics

Poq: Projection-based Runtime Assertions for Debugging on a Quantum Computer

Gushu Li, Li Zhou, Nengkun Yu +3 more·Nov 28, 2019

In this paper, we propose Proq, a runtime assertion scheme for testing and debugging quantum programs on a quantum computer. The predicates in Proq are represented by projections (or equivalently, closed subspaces of the state space), following Birkh...

Computer SciencePhysics

A little bit of classical magic to achieve quantum speedup

D. Kaszlikowski, P. Kurzyński·Nov 28, 2019

We introduce nebit, a classical bit with a signed probability distribution. We quantify its entropy using Szekely theorem on signed probability measures and show that classical stochastic dynamics supplemented with nebits can achieve or even exceed t...

PhysicsComputer Science

Higher rank matricial ranges and hybrid quantum error correction

Ningping Cao, D. Kribs, Chi-Kwong Li +3 more·Nov 28, 2019

ABSTRACT We introduce and initiate the study of a family of higher rank matricial ranges, taking motivation from hybrid classical and quantum error correction coding theory and its operator algebra framework. In particular, for a noisy quantum channe...

MathematicsPhysics

A Data Driven Approach to Learning The Hamiltonian Matrix in Quantum Mechanics

Jordan Burns, D. Maughan, Yih Sung·Nov 28, 2019

We present a new machine learning technique which calculates a real-valued, time independent, finite dimensional Hamiltonian matrix from only experimental data. A novel cost function is given along with a proof that the cost function has the theoreti...

Computer SciencePhysics

Path-Independent Quantum Gates with Noisy Ancilla.

Wen-Long Ma, Mengzhen Zhang, Yat Wong +5 more·Nov 27, 2019

Ancilla systems are often indispensable to universal control of a nearly isolated quantum system. However, ancilla systems are typically more vulnerable to environmental noise, which limits the performance of such ancilla-assisted quantum control. To...

MedicineComputer SciencePhysics

Real-time decoding of stabilizer measurements in a bit-flip code

D. Ristè, L. Govia, Brian F. Donovan +5 more·Nov 27, 2019

Although qubit coherence times and gate fidelities are continuously improving, logical encoding is essential to achieve fault tolerance in quantum computing. In most encoding schemes, correcting or tracking errors throughout the computation is necess...

PhysicsComputer Science

Performance optimisation for drift-robust fidelity improvement of two-qubit gates.

G. White, C. Hill, L. Hollenberg·Nov 27, 2019

Quantum system characterisation techniques represent the front-line in the identification and mitigation of noise in quantum computing, but can be expensive in terms of quantum resources and time to repeatedly employ. Another challenging aspect is th...

Computer SciencePhysics

Approximating Permanent of Random Matrices with Vanishing Mean: Made Better and Simpler

Zhengfeng Ji, Zhihan Jin, Pinyan Lu·Nov 27, 2019

The algorithm and complexity of approximating the permanent of a matrix is an extensively studied topic. Recently, its connection with quantum supremacy and more specifically BosonSampling draws special attention to the average-case approximation pro...

Computer SciencePhysicsMathematics

Qubit regularized $O(N)$ nonlinear sigma models

Hersh Singh·Nov 27, 2019

Motivated by the prospect of quantum simulation of quantum field theories, we formulate the O(N) nonlinear sigma model as a “qubit” model with an (N + 1)-dimensional local Hilbert space at each lattice site. Using an efficient worm algorithm in the w...

Physics

Algorithm for automated tuning of a quantum dot into the single-electron regime

M. Lapointe-Major, Olivier Germain, J. C. Lemyre +4 more·Nov 26, 2019

We report an algorithm designed to perform computer-automated tuning of a single quantum dot with a charge sensor. The algorithm performs an adaptive measurement sequence of sub-sized stability diagrams until the single-electron regime is identified ...

Physics

Protecting quantum coherences from static noise and disorder

Chahan M. Kropf·Nov 26, 2019

Quantum coherences are paramount resources for applications, such as quantum-enhanced light-harvesting or quantum computing, which are fragile against environmental noise. We here derive generalized quantum master equations using perturbation theory ...

Physics

Limitations of Clustering Using Quantum Persistent Homology

N. Neumann, S. D. Breeijen·Nov 25, 2019

Different algorithms can be used for clustering purposes with data sets. On of these algorithms, uses topological features extracted from the data set to base the clusters on. The complexity of this algorithm is however exponential in the number of da...

PhysicsMathematicsComputer Science
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