Papers

B. Dive, Alexander Pitchford, F. Mintert +1 more·Jan 6, 2017

Quantum simulators, machines that can replicate the dynamics of quantum systems, are being built as useful devices and are seen as a stepping stone to universal quantum computers. A key difference between the two is that computers have the ability to...

G. Guerreschi, M. Smelyanskiy·Jan 5, 2017

A novel class of hybrid quantum-classical algorithms based on the variational approach have recently emerged from separate proposals addressing, for example, quantum chemistry and combinatorial problems. These algorithms provide an approximate soluti...

Edwin Barnes, C. Arenz, Alexander Pitchford +1 more·Dec 30, 2016

Although single and two-qubit gates are sufficient for universal quantum computation, single-shot three-qubit gates greatly simplify quantum error correction schemes and algorithms. We design fast, high-fidelity three-qubit entangling gates based on ...

R. Versluis, R. Versluis, S. Poletto +8 more·Dec 24, 2016

We present a scalable scheme for executing the error-correction cycle of a monolithic surface-code fabric composed of fast-flux-tunable transmon qubits with nearest-neighbor coupling. An eight-qubit unit cell forms the basis for repeating both the qu...

Ritajit Majumdar, Saikat Basu, Priyanka Mukhopadhyay +1 more·Dec 23, 2016

Descriptions of quantum algorithms, communication etc. protocols assume the existence of closed quantum system. However, real life quantum systems are open and are highly sensitive to errors. Hence error correction is of utmost importance if quantum ...

Theodore J. Yoder, Isaac H. Kim·Dec 14, 2016

The surface code is one of the most successful approaches to topological quantum error-correction. It boasts the smallest known syndrome extraction circuits and correspondingly largest thresholds. Defect-based logical encodings of a new variety calle...

C. Chamberland, Joel J. Wallman, Stefanie J. Beale +1 more·Dec 8, 2016

Quantum error correction is instrumental in protecting quantum systems from noise in quantum computing and communication settings. Pauli channels can be efficiently simulated and threshold values for Pauli error rates under a variety of error-correct...

D. McKay, C. J. Wood, S. Sheldon +2 more·Dec 2, 2016

For superconducting qubits, microwave pulses drive rotations around the Bloch sphere. The phase of these drives can be used to generate zero-duration arbitrary virtual $Z$ gates, which, combined with two ${X}_{\ensuremath{\pi}/2}$ gates, can generate...

L. Theis, F. Wilhelm·Nov 8, 2016

We review a time-dependent version of the Schrieffer-Wolff transformation that accounts for real-time control of system parameters, soon to be rendered possible on a broad basis due to technical progress. The dispersive regime of N multilevel systems c...

Frank Tabakin·Nov 2, 2016

A model master equation suitable for quantum computing dynamics is presented. In an ideal quantum computer (QC), a system of qubits evolves in time unitarily and, by virtue of their entanglement, interfere quantum mechanically to solve otherwise intr...

Tanay Roy, S. Kundu, M. Chand +7 more·Oct 25, 2016

We present the "trimon", a multi-mode superconducting circuit implementing three qubits with all-to-all longitudinal coupling. This always-on interaction enables simple implementation of generalized controlled-NOT gates which form a universal set. Fu...

Hai‐Rui Wei, Pei Zhu·Oct 24, 2016

It is desirable to implement an efficient quantum information process demanding fewer quantum resources. We designed two compact quantum circuits for determinately implementing four-qubit Toffoli and Fredkin gates on single-photon systems in both the...

E. Nikahd, M. S. Zamani, M. Sedighi·Oct 11, 2016

As there is no quantum error correction code with universal set of transversal gates, several approaches have been proposed which, in combination of transversal gates, make universal fault-tolerant quantum computation possible. Magic state distillati...

Mateus de Oliveira Oliveira·Sep 30, 2016

We show that any quantum circuit of treewidth $t$, built from $r$-qubit gates, requires at least $\Omega(\frac{n^{2}}{2^{O(r\cdot t)}\cdot \log^4 n})$ gates to compute the element distinctness function. Our result generalizes a near-quadratic lower b...

James R. Wootton·Sep 25, 2016

Currently, the mainstream approach to quantum computing is through surface codes. One way to store and manipulate quantum information with these to create defects in the codes which can be moved and used as if they were particles. Specifically, they ...

Y. Nakata, Christoph Hirche, M. Koashi +1 more·Sep 22, 2016

We provide new constructions of unitary $t$-designs for general $t$ on one qudit and $N$ qubits, and propose a design Hamiltonian, a random Hamiltonian of which dynamics always forms a unitary design after a threshold time, as a basic framework to in...

A. Paler, R. Wille, S. Devitt·Sep 3, 2016

Quantum information processing is expressed using quantum bits (qubits) and quantum gates which are arranged in the terms of quantum circuits. Here, each qubit is associated to a quantum circuit wire which is used to conduct the desired operations. M...

Benjamin Cruikshank, K. Jacobs·Aug 29, 2016

von Neumann's classic "multiplexing" method is unique in achieving high-threshold fault-tolerant classical computation (FTCC), but has several significant barriers to implementation: (i) the extremely complex circuits required by randomized connectio...

Y. Takahashi, S. Tani·Aug 25, 2016

We study the computational power of shallow quantum circuits with $n$ input qubits, one output qubit, and two types of ancillary qubits: $O(\log n)$ initialized and $n^{O(1)}$ uninitialized qubits. The initial state of the uninitialized ancillary qub...

Cody Jones, M. Fogarty, A. Morello +3 more·Aug 22, 2016

We design and analyze a logical qubit composed of a linear array of electron spins in semiconductor quantum dots. To avoid the difficulty of fully controlling a two-dimensional array of dots, we adapt spin control and error correction to a one-dimens...