Quantum Brain

Papers

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

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31,850

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15,851 papers in 12 months (-35% vs prior quarter)

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31,850 papers found

What Randomized Benchmarking Actually Measures.

T. Proctor, K. Rudinger, K. Young +2 more·Feb 7, 2017

Randomized benchmarking (RB) is widely used to measure an error rate of a set of quantum gates, by performing random circuits that would do nothing if the gates were perfect. In the limit of no finite-sampling error, the exponential decay rate of the...

MathematicsPhysicsMedicine

Quantum Correlations in Nonlocal BosonSampling

F. Shahandeh, A. Lund, T. Ralph·Feb 7, 2017

Determination of the quantum nature of correlations between two spatially separated systems plays a crucial role in quantum information science. Of particular interest is the questions of if and how these correlations enable quantum information proto...

PhysicsComputer ScienceMedicineMathematics

Experimental comparison of two quantum computing architectures

N. Linke, D. Maslov, M. Rötteler +5 more·Feb 7, 2017

Significance Quantum computers are an emerging technology promising to be vastly more powerful at solving certain problems than any conventional computer. These devices are now moving out of the laboratory and becoming generally programmable. This al...

Computer SciencePhysicsMedicine

Efficient detection of useful long-range entanglement in imperfect cluster states

T. Nutz, A. Milne, P. Shadbolt +1 more·Feb 7, 2017

Photonic cluster states are a crucial resource for optical quantum computing. Recently a quantum dot single photon source has been demonstrated to produce strings of photons in a linear cluster state, but high photon loss rates make it impossible to ...

Physics

A class of time-energy uncertainty relations for time-dependent Hamiltonians

T. Kieu·Feb 2, 2017

A new class of time-energy uncertainty relations is directly derived from the Schrödinger equations for time-dependent Hamiltonians. Only the initial states and the Hamiltonians, but neither the instantaneous eigenstates nor the full time-dependent w...

MathematicsPhysics

Quantum nonlinear optics without photons

R. Stassi, V. Macrì, A. F. Kockum +4 more·Feb 2, 2017

Spontaneous parametric down-conversion is a well-known process in quantum nonlinear optics in which a photon incident on a nonlinear crystal spontaneously splits into two photons. Here we propose an analogous physical process where one excited atom d...

PhysicsMathematics

Quantum jumps, superpositions, and the continuous evolution of quantum states

R. Dick·Feb 1, 2017

Abstract The apparent dichotomy between quantum jumps on the one hand, and continuous time evolution according to wave equations on the other hand, provided a challenge to Bohr's proposal of quantum jumps in atoms. Furthermore, Schrodinger's time-dep...

Physics

Quantum algorithms for computing short discrete logarithms and factoring RSA integers

Martin Ekerå, J. Håstad·Feb 1, 2017

We generalize the quantum algorithm for computing short discrete logarithms previously introduced by Ekera [2] so as to allow for various tradeoffs between the number of times that the algorithm need be executed on the one hand, and the complexity of...

Computer ScienceMathematicsPhysics

Fully graphical treatment of the quantum algorithm for the Hidden Subgroup Problem

S. Gogioso, A. Kissinger·Jan 30, 2017

The abelian Hidden Subgroup Problem (HSP) is extremely general, and many problems with known quantum exponential speed-up (such as integers factorisation, the discrete logarithm and Simon's problem) can be seen as specific instances of it. The tradit...

Computer ScienceMathematicsPhysics

Schrödinger cat and Werner state disentanglement simulated by trapped ion systems

V. Bittencourt, A. Bernardini·Jan 30, 2017

Disentanglement and loss of quantum correlations due to one global collective noise effect are described for two-qubit Schrödinger cat and Werner states of a four level trapped ion quantum system. Once the Jaynes–Cummings ionic interactions are mappe...

Physics

Quantum Monte Carlo annealing with multi-spin dynamics

G. Mazzola, M. Troyer·Jan 30, 2017

We introduce a novel simulated quantum annealing (SQA) algorithm which employs a multispin quantum fluctuation operator. At variance with the usual transverse field, short-range two-spin flip interactions are included in the driver Hamiltonian. A Qua...

MathematicsPhysics

Experimental protection of arbitrary states in a two-qubit subspace by nested Uhrig dynamical decoupling

Harpreet Singh, Arvind, K. Dorai·Jan 28, 2017

We experimentally demonstrate the efficacy of a three-layer nested Uhrig dynamical decoupling (NUDD) sequence to preserve arbitrary quantum states in a two-dimensional subspace of the four-dimensional two-qubit Hilbert space, on an NMR quantum inform...

Physics

Tapering off qubits to simulate fermionic Hamiltonians

S. Bravyi, J. Gambetta, Antonio Mezzacapo +1 more·Jan 27, 2017

We discuss encodings of fermionic many-body systems by qubits in the presence of symmetries. Such encodings eliminate redundant degrees of freedom in a way that preserves a simple structure of the system Hamiltonian enabling quantum simulations with ...

PhysicsMathematics

Non-Abelian holonomic transformation in the presence of classical noise

J. Jing, C. Lam, L. -A. Wu·Jan 27, 2017

It is proposed that high-speed universal quantum gates can be realized by using non-Abelian holonomic transformation. A cyclic evolution path which brings the system periodically back to a degenerate qubit subspace is crucial to holonomic quantum com...

Physics

Quantum dark solitons as qubits in Bose-Einstein condensates

M. I. Shaukat, E. Castro, H. Terccas·Jan 26, 2017

We study the possibility of using dark soliton in quasi one dimensional Bose Einstein condensates to produce two level system (qubits) by exploiting the intrinsic nonlinear and the coherent nature of the matter waves. We calculate the soliton spectru...

Physics

Mølmer–Sørensen entangling gate for cavity QED systems

Hiroki Takahashi, Pedro Nevado, M. Keller·Jan 26, 2017

The Mølmer–Sørensen gate is a state-of-the-art entangling gate in ion trap quantum computing where the gate fidelity can exceed 99%. Here we propose an analogous implementation in the setting of cavity QED. The cavity photon mode acts as the bosonic ...

Physics

Non-stoquastic Hamiltonians in quantum annealing via geometric phases

W. Vinci, Daniel A. Lidar·Jan 25, 2017

We argue that a complete description of quantum annealing implemented with continuous variables must take into account the non-adiabatic Aharonov-Anandan geometric phase that arises when the system Hamiltonian changes during the anneal. We show that ...

Physics

Ultralow 1/f Noise in a Heterostructure of Superconducting Epitaxial Cobalt Disilicide Thin Film on Silicon.

S. Chiu, S. Yeh, Chien-Jyun Chiou +3 more·Jan 24, 2017

High-precision resistance noise measurements indicate that the epitaxial CoSi2/Si heterostructures at 150 and 2 K (slightly above its superconducting transition temperature Tc of 1.54 K) exhibit an unusually low 1/f noise level in the frequency range...

MedicineMaterials SciencePhysics

Quantum entanglement, sum of squares, and the log rank conjecture

B. Barak, Pravesh Kothari, David Steurer·Jan 23, 2017

For every constant ε>0, we give an exp(Õ(∞n))-time algorithm for the 1 vs 1 - ε Best Separable State (BSS) problem of distinguishing, given an n2 x n2 matrix ℳ corresponding to a quantum measurement, between the case that there is a separable (i.e., ...

Computer ScienceMathematicsPhysics

Electrically driving nuclear spin qubits with microwave photonic bangap resonators

A. Sigillito, A. Tyryshkin, T. Schenkel +2 more·Jan 23, 2017

The electronic and nuclear spin degrees of freedom for donor impurities in semiconductors form ultra coherent two-level systems that are useful for quantum information applications. Spins naturally have magnetic dipoles, so alternating current (AC) m...

Physics
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