Papers

E. Campbell, Ankur Khurana, A. Montanaro·Oct 12, 2018

Quantum algorithms can deliver asymptotic speedups over their classical counterparts. However, there are few cases where a substantial quantum speedup has been worked out in detail for reasonably-sized problems, when compared with the best classical ...

K. Rudinger, T. Proctor, Dylan Langharst +3 more·Oct 12, 2018

Gates in error-prone quantum information processors are often modeled using sets of one- and two-qubit process matrices, the standard model of quantum errors. However, the results of quantum circuits on real processors often depend on additional exte...

Jiayu Zhang·Oct 11, 2018

A delegation scheme allows a computationally weak client to use a server's resources to help it evaluate a complex circuit without leaking any information about the input (other than its length) to the server. In this paper, we consider delegation sc...

W. Ho, Cheryne Jonay, T. Hsieh·Oct 11, 2018

State preparation protocols ideally require as minimal a circuit depth as possible, in order to be implemented in near-term quantum devices. Motivated by long range interactions (LRI) intrinsic to many experimental platforms (trapped ions, Rydberg at...

Kanav Setia, S. Bravyi, Antonio Mezzacapo +1 more·Oct 11, 2018

Simulation of fermionic many-body systems on a quantum computer requires a suitable encoding of fermionic degrees of freedom into qubits. Here we revisit the Superfast Encoding introduced by Kitaev and one of the authors. This encoding maps a target ...

Hai-Jing Song, Qi-Kai He, Zheng An +1 more·Oct 10, 2018

We propose a bang-bang control scheme to enhance photon generation from the vacuum via the counter-rotating wave (CRW) interaction, and develop a pruning greedy algorithm (PGA) to identify the optimal control sequence. Our numerical results demonstra...

Michael Jarret, Brad Lackey, Aike Liu +1 more·Oct 10, 2018

Quantum adiabatic optimization (QAO) is performed using a time-dependent Hamiltonian $H(s)$ with spectral gap $\gamma(s)$. Assuming the existence of an oracle $\Gamma$ such that $\gamma_\min = \Theta\left(\min_s\Gamma(s)\right)$, we provide an algori...

Yuan Xu, Yuwei Ma, W. Cai +11 more·Oct 10, 2018

To realize fault-tolerant quantum computing, it is necessary to store quantum information in logical qubits with error correction functions, realized by distributing a logical state among multiple physical qubits or by encoding it in the Hilbert spac...

R. Kosut, C. Arenz, H. Rabitz·Oct 10, 2018

The control landscape of a quantum system A interacting with another quantum system B is studied. Only system A is accessible through time dependent controls, while system B is not accessible. The objective is to find controls that implement a desire...

R. Movassagh·Oct 10, 2018

One-parameter interpolations between any two unitary matrices (e.g., quantum gates) $U_1$ and $U_2$ along efficient paths contained in the unitary group are constructed. Motivated by applications, we propose the continuous unitary path $U(\theta)$ ob...

Iris Cong, Soonwon Choi, M. Lukin·Oct 9, 2018

Neural network-based machine learning has recently proven successful for many complex applications ranging from image recognition to precision medicine. However, its direct application to problems in quantum physics is challenging due to the exponent...

H. Qin·Oct 9, 2018

Linear Hamiltonian systems with time-dependent coefficients are of importance to nonlinear Hamiltonian systems, accelerator physics, plasma physics, and quantum physics. It is shown that the solution map of a linear Hamiltonian system with time-depen...

D. Aharonov, Y. Touati·Oct 9, 2018

We provide an $\Omega(log(n))$ lower bound for the depth of any quantum circuit generating the unique groundstate of Kitaev's spherical code. No circuit-depth lower bound was known before on this code in the general case where the gates can connect q...

C. Kokail, C. Maier, R. van Bijnen +8 more·Oct 8, 2018

Hybrid classical–quantum algorithms aim to variationally solve optimization problems using a feedback loop between a classical computer and a quantum co-processor, while benefiting from quantum resources. Here we present experiments that demonstrate ...

Antoine Grospellier, Anirudh Krishna·Oct 8, 2018

Hypergraph product codes introduced by Tillich and Zemor are a class of quantum LDPC codes with constant rate and distance scaling with the square-root of the block size. Quantum expander codes, a subclass of these codes, can be decoded using the lin...

L. Kocia, P. Love·Oct 8, 2018

One of the lowest-order corrections to Gaussian quantum mechanics in infinite-dimensional Hilbert spaces are Airy functions: a uniformization of the stationary phase method applied in the path integral perspective. We introduce a "periodized stationa...

Kunal Das, Arindam Sadhu·Oct 8, 2018

In this work, a constant time Quantum searching algorithm over a datasets is proposed and subsequently the algorithm is executed in real chip quantum computer developed by IBM Quantum experience (IBMQ). QISKit, the software platform developed by IBM ...

Cheng Zhang, K. Zhou, Wei Feng +1 more·Oct 5, 2018

Designing high-precision and efficient schemes is of crucial importance for quantum parameter estimation in practice. The estimation scheme based on continuous quantum measurement is one possible type of this, which looks also the most natural choice...

I. Ho·Oct 5, 2018

In order to quickly study quantum devices in transient problems, this work demonstrates an analytical algorithm to solve the Hartree potential associated with charge fluctuations in the time-dependent non-equilibrium green function (TDNEGF) method. W...

M. Steudtner, S. Wehner·Oct 5, 2018

Quantum simulation of fermionic systems is a promising application of quantum computers, but to program them, we need to map fermionic states and operators to qubit states and quantum gates. While quantum processors may be built as two-dimensional qu...