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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4,120 papers found

Quantum Searchable Encryption for Cloud Data Based on Full-Blind Quantum Computation

Wenjie Liu, Yinsong Xu, Wenjie Liu +2 more·Dec 18, 2019

Searchable encryption (SE) is a positive way to protect users sensitive data in cloud computing setting, while preserving search ability on the server side, i.e., it allows the server to search encrypted data without leaking information about the pla...

Computer SciencePhysics

Quantum natural gradient generalized to noisy and nonunitary circuits

Bálint Koczor, S. Benjamin·Dec 18, 2019

Variational quantum algorithms are promising tools whose efficacy depends on their optimisation method. For noise-free unitary circuits, the quantum generalisation of natural gradient descent has been introduced and shown to be equivalent to imaginar...

Physics

Optimised fast gates for quantum computing with trapped ions

Evan P. G. Gale, Z. Mehdi, L. Oberg +3 more·Dec 17, 2019

We present an efficient approach to optimising pulse sequences for implementing fast entangling two-qubit gates on trapped ion quantum information processors. This a two-phase procedure for optimising gate fidelity. The first phase involves a global ...

Physics

Quantum advantage from energy measurements of many-body quantum systems

Leonardo Novo, Juan Bermejo-Vega, R. Garc'ia-Patr'on·Dec 13, 2019

The problem of sampling outputs of quantum circuits has been proposed as a candidate for demonstrating a quantum computational advantage (sometimes referred to as quantum "supremacy"). In this work, we investigate whether quantum advantage demonstrat...

Computer SciencePhysics

State preparation based on quantum phase estimation

Jian Zhao, Yuchun Wu, G. Guo +1 more·Dec 11, 2019

State preparation is a process encoding the classical data into the quantum systems. Based on quantum phase estimation, we propose the specific quantum circuits for a deterministic state preparation algorithm and a probabilistic state preparation alg...

Computer SciencePhysics

Iterative quantum amplitude estimation

Dmitry Grinko, Julien Gacon, Christa Zoufal +1 more·Dec 11, 2019

We introduce a variant of Quantum Amplitude Estimation (QAE), called Iterative QAE (IQAE), which does not rely on Quantum Phase Estimation (QPE) but is only based on Grover’s Algorithm, which reduces the required number of qubits and gates. We provid...

MathematicsPhysics

Grover Adaptive Search for Constrained Polynomial Binary Optimization

Austin Gilliam, Stefan Woerner, Constantin Gonciulea·Dec 9, 2019

In this paper we discuss Grover Adaptive Search (GAS) for Constrained Polynomial Binary Optimization (CPBO) problems, and in particular, Quadratic Unconstrained Binary Optimization (QUBO) problems, as a special case. GAS can provide a quadratic speed...

Computer SciencePhysics

Implementation of the XY interaction family with calibration of a single pulse

D. Abrams, N. Didier, Blake R. Johnson +2 more·Dec 9, 2019

Near-term applications of quantum information processors will rely on optimized circuit implementations to minimize gate depth and therefore mitigate the impact of gate errors in noisy intermediate-scale quantum (NISQ) computers. More expressive gate...

PhysicsComputer Science

Heuristics for Quantum Compiling with a Continuous Gate Set

M. Davis, Ethan Smith, Ana Tudor +3 more·Dec 5, 2019

We present an algorithm for compiling arbitrary unitaries into a sequence of gates native to a quantum processor. As accurate CNOT gates are hard for the foreseeable Noisy- Intermediate-Scale Quantum devices era, our A* inspired algorithm attempts to...

Computer SciencePhysics

Quantum unary approach to option pricing

Sergi Ramos-Calderer, Adrián Pérez-Salinas, Diego García-Martín +4 more·Dec 3, 2019

We present a novel quantum algorithm for European option pricing in finance, where the key idea is to work in the unary representation of the asset value. The algorithm needs novel circuitry and is divided in three parts: first, the amplitude distrib...

PhysicsComputer Science

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

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

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

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

Quantum algorithms for disordered physics

A. Alexandru, P. Bedaque, S. Lawrence·Nov 25, 2019

We show how a quantum computer may efficiently simulate a disordered Hamiltonian, by incorporating a pseudo-random number generator directly into the time evolution circuit. This technique is applied to quantum simulation of few-body disordered syste...

Physics

Thermodynamic analysis of quantum error-correcting engines

G. Landi, A. L. Fonseca de Oliveira, Efrain Buksman·Nov 14, 2019

Quantum error correcting codes can be cast in a way which is strikingly similar to a quantum heat engine undergoing an Otto cycle. In this paper we strengthen this connection further by carrying out a complete assessment of the thermodynamic properti...

PhysicsComputer Science

Variational Circuit Compiler for Quantum Error Correction

Xiaosi Xu, S. Benjamin, Xiao Yuan·Nov 13, 2019

Quantum error correction is vital for implementing universal quantum computing. A key component is the encoding circuit that maps a product state of physical qubits into the encoded multipartite entangled logical state. Known methods are typically no...

PhysicsComputer Science

Portfolio rebalancing experiments using the Quantum Alternating Operator Ansatz

Mark Hodson, Brendan Ruck, Hugh Ong +2 more·Nov 13, 2019

This paper investigates the experimental performance of a discrete portfolio optimization problem relevant to the financial services industry on the gate-model of quantum computing. We implement and evaluate a portfolio rebalancing use case on an ide...

Computer SciencePhysics

Quantum circuit for the fast Fourier transform

Ryo Asaka, K. Sakai, Ryoko Yahagi·Nov 8, 2019

We propose an implementation of the algorithm for the fast Fourier transform (FFT) as a quantum circuit consisting of a combination of some quantum gates. In our implementation, a data sequence is expressed by a tensor product of vector spaces. Namel...

PhysicsComputer Science
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