Quantum Brain

Papers

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

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15,671 papers in 12 months (-39% vs prior quarter)

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Hardware platform mentions in abstractsPhotonic leads

31,611 papers found

Entanglement-Free Parameter Estimation of Generalized Pauli Channels

Junaid ur Rehman, Hyundong Shin·Feb 1, 2021

We propose a parameter estimation protocol for generalized Pauli channels acting on d-dimensional Hilbert space. The salient features of the proposed method include product probe states and measurements, the number of measurement configurations linea...

PhysicsComputer Science

Special-Purpose Quantum Processor Design

Bing-Han Lu, Yuchun Wu, Wei-cheng Kong +2 more·Feb 1, 2021

Full connectivity of qubits is necessary for most quantum algorithms, which is difficult to directly implement on Noisy Intermediate-Scale Quantum processors. However, inserting swap gate to enable the two-qubit gates between uncoupled qubits signifi...

Physics

Sampling electronic structure QUBOs with Ocean and Mukai solvers

A. Teplukhin, B. Kendrick, S. Mniszewski +7 more·Feb 1, 2021

The most advanced D-Wave Advantage quantum annealer has 5000+ qubits, however, every qubit is connected to a small number of neighbors. As such, implementation of a fully-connected graph results in an order of magnitude reduction in qubit count. To c...

Physics

Bandgap optimization in combinatorial graphs with tailored ground states: application in quantum annealing

Siddharth Srivastava, V. Sundararaghavan·Jan 31, 2021

A mixed-integer linear programming (MILP) formulation is presented for parameter estimation of the Potts model. Two algorithms are developed; the first method estimates the parameters such that the set of ground states replicate the user-prescribed d...

Computer ScienceMathematicsPhysics

Comparison of Cloud-Based Ion Trap and Superconducting Quantum Computer Architectures

S. Blinov, Benwei Wu, C. Monroe·Jan 31, 2021

Quantum computing represents a radical departure from conventional approaches to information processing, offering the potential for solving problems that can never be approached classically. While large scale quantum computer hardware is still in dev...

Computer SciencePhysics

Simulating Many-Body Systems with a Projective Quantum Eigensolver

Nicholas H Stair, Francesco A. Evangelista·Jan 31, 2021

We present a new hybrid quantum-classical algorithm for optimizing unitary coupled-cluster (UCC) wave functions deemed the projective quantum eigensolver (PQE), amenable to near-term noisy quantum hardware. Contrary to variational quantum algorithms,...

Physics

Entanglement in bipartite quantum systems: Euclidean volume ratios and detectability by Bell inequalities

A. Sauer, J. Z. Bernád, H. Moreno +1 more·Jan 30, 2021

Euclidean volume ratios between quantum states with positive partial transpose and all quantum states in bipartite systems are investigated. These ratios allow a quantitative exploration of the typicality of entanglement and of its detectability by B...

Physics

Entropic barriers as a reason for hardness in both classical and quantum algorithms

Matteo Bellitti, F. Ricci-Tersenghi, A. Scardicchio·Jan 30, 2021

We study both classical and quantum algorithms to solve a hard optimization problem, namely 3–XORSAT on 3–regular random graphs. By introducing a new quasi–greedy algorithm that is not allowed to jump over large energy barriers, we show that the prob...

Physics

A Quantum Interpretation of Bunched Logic & Quantum Separation Logic

Li Zhou, G. Barthe, Justin Hsu +2 more·Jan 30, 2021

We propose a model of the substructural logic of Bunched Implications (BI) that is suitable for reasoning about quantum states. In our model, the separating conjunction of BI describes separable quantum states. We develop a program logic where pre- a...

Computer SciencePhysics

Qubits made by advanced semiconductor manufacturing

A. Zwerver, T. Krahenmann, T. Watson +26 more·Jan 29, 2021

Silicon spin qubits can be fabricated in a 300 mm semiconductor manufacturing facility using all-optical lithography and fully industrial processing. Full-scale quantum computers require the integration of millions of qubits, and the potential of usi...

Physics

On solving classes of positive-definite quantum linear systems with quadratically improved runtime in the condition number

Davide Orsucci, V. Dunjko·Jan 28, 2021

Quantum algorithms for solving the Quantum Linear System (QLS) problem are among the most investigated quantum algorithms of recent times, with potential applications including the solution of computationally intractable differential equations and sp...

PhysicsComputer Science

Fast Estimation of Outcome Probabilities for Quantum Circuits

Hakop Pashayan, Oliver Reardon-Smith, K. Korzekwa +1 more·Jan 28, 2021

We present two classical algorithms for the simulation of universal quantum circuits on $n$ qubits constructed from $c$ instances of Clifford gates and $t$ arbitrary-angle $Z$-rotation gates such as $T$ gates. Our algorithms complement each other by ...

Physics

A highly tunable quadruple quantum dot in a narrow bandgap semiconductor InAs nanowire.

Jingwei Mu, Shaoyun Huang, Zhi-Hai Liu +7 more·Jan 27, 2021

Quantum dots (QDs) made from semiconductors are among the most promising platforms for the development of quantum computing and simulation chips, and they have the advantages of high density integration and compatibility with the standard semiconduct...

PhysicsMaterials ScienceMedicine

Broad-band spectroscopy of a vanadyl porphyrin: a model electronuclear spin qudit†

I. Gimeno, A. Urtizberea, Juan Román-Roche +5 more·Jan 27, 2021

We explore how to encode more than a qubit in vanadyl porphyrin molecules hosting a S = 1/2 electronic spin coupled to a I = 7/2 nuclear spin. The spin Hamiltonian and its parameters, as well as the spin dynamics, have been determined via a combinati...

MedicinePhysics

Quantum simulation of molecules without fermionic encoding of the wave function

D. Mazziotti, Scott E. Smart, A. Mazziotti·Jan 27, 2021

Molecular simulations generally require fermionic encoding in which fermion statistics are encoded into the qubit representation of the wave function. Recent calculations suggest that fermionic encoding of the wave function can be bypassed, leading t...

Physics

Compact Ion-Trap Quantum Computing Demonstrator

Ivan Pogorelov, T. Feldker, Christian D. Marciniak +13 more·Jan 27, 2021

Quantum information processing is steadily progressing from a purely academic discipline towards applications throughout science and industry. Transitioning from lab-based, proof-of-concept experiments to robust, integrated realizations of quantum in...

Physics

Impact of correlations and heavy tails on quantum error correction

B. D. Clader, Colin J. Trout, J. Barnes +3 more·Jan 27, 2021

We show that space- and time-correlated single-qubit rotation errors can lead to high-weight errors in a quantum circuit when the rotation angles are drawn from heavy-tailed distributions. This leads to a breakdown of quantum error correction, yieldi...

Physics

An Open-source Library of Large Integer Polynomial Multipliers

Malik Imran, Zain Ul Abideen, S. Pagliarini·Jan 27, 2021

Polynomial multiplication is a bottleneck in most of the public-key cryptography protocols, including Elliptic-curve cryptography and several of the post-quantum cryptography algorithms presently being studied. In this paper, we present a library of ...

Computer Science

Classical simulation of lossy boson sampling using matrix product operators

Changhun Oh, Kyungjoo Noh, Bill Fefferman +1 more·Jan 27, 2021

Characterizing the computational advantage from noisy intermediate-scale quantum (NISQ) devices is an important task from theoretical and practical perspectives. Here, we numerically investigate the computational power of NISQ devices focusing on bos...

Physics

Spin-Polarized Initialization and Readout for Single-Qubit State Tomography

M. B. Sambú, L. Sanz, F. M. Souza·Jan 26, 2021

We propose a theoretical protocol for reconstructing the density matrix of a single-electron spin qubit using spin-polarized transport. The system consists of a quantum dot coupled to ferromagnetic reservoirs and subject to a magnetic field lying in ...

Quantum PhysicsMesoscale Physics
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