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Physics

Quantum information science

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Displaying 501 - 525 of 1687

A post-processing-free single-photon random number generator with ultra-low latency.

December 10, 2018
Author(s)
Michael A. Wayne, Joshua C. Bienfang, Zachary H. Levine, Alan L. Migdall
The low-latency requirements of a practical loophole-free Bell test preclude time-consuming post- processing steps that are often used to improve the statistical quality of a physical random number generator (RNG). Here we demonstrate a post-processing

Kinetic Inductance Traveling Wave Amplifiers For Multiplexed Qubit Readout

December 10, 2018
Author(s)
Leonardo Ranzani, K. C. Fong, G. Ribell, Tomas A. Ohki, David P. Pappas, Mustafa Bal, Xian Wu, Robert P. Erickson, Junling Long, Hsiang S. Ku
We describe a kinetic inductance traveling-wave (KIT) amplifier suitable for superconducting quantum information measurements and characterize its wideband scattering and noise properties. We use mechanical microwave switches to calibrate the four

Spin decoherence in a two-qubit CPHASE gate: the critical role of tunneling noise

November 27, 2018
Author(s)
Peihao Huang, Neil M. Zimmerman, Garnett W. Bryant
The rapid progress in the manipulation and detection of semiconductor spin qubits enables the experimental demonstration of a high fidelity two-qubit logic gate, which is necessary for universal quantum computing. Here, we study the decoherence of two

Spin relaxation of a donor electron coupled to interface states

November 16, 2018
Author(s)
Peihao Huang, Garnett W. Bryant
An electron spin qubit in a silicon donor atom is a promising candidate for quantum information processing because of its long coherence time. To be sensed with a single-electron transistor, the donor atom is usually located near an interface, where the

The Complexity and Verification of Quantum Random Circuit Sampling

October 29, 2018
Author(s)
Adam Bouland, William J. Fefferman, Chinmay Nirkhe, Umesh Vazirani
A critical milestone on the path to useful quantum computers is the demonstration of a quantum computation that is prohibitively hard for classical computers -- a task referred to as quantum supremacy. A leading near-term candidate is sampling from the

Recovering quantum gates from few average gate fidelities

October 24, 2018
Author(s)
Yi-Kai Liu, Ingo Roth, Richard Kueng, Shelby Kimmel, David Gross, Jens Eisert, Martin Kliesch
Characterizing quantum processes is a key task in and constitutes a challenge for the development of quantum technologies, especially at the noisy intermediate scale of today's devices. One method for characterizing processes is randomized benchmarking

On the scalability of parametric down-conversion for generating higher-order Fock states

October 18, 2018
Author(s)
Thomas Gerrits, Adriana Lita, Sae Woo Nam, Johannes Tiedau, Tim J. Bartley, Georg Harder, Christine Silberhorn
Spontaneous parametric down-conversion (SPDC) is the most widely-used method to generate higher-order Fock states (n>2). Yet, a consistent performance analysis from fundamental principles is missing. Here we address this problem by analyzing state fidelity

Joint Quantum State and Measurement Tomography with Incomplete Measurements

October 12, 2018
Author(s)
Adam C. Keith, Charles H. Baldwin, Scott C. Glancy, Emanuel H. Knill
Estimation of quantum states and measurements is crucial for the implementation of quantum information protocols. The standard method for each is quantum tomography (QT). However, QT suffers from systematic errors caused by imperfect knowledge of the

Randomness Extraction from Bell Violation with Continuous Parametric Down-Conversion

October 9, 2018
Author(s)
Thomas Gerrits, Sae Woo Nam, Adriana Lita, Lijiong Shen, Jianwei Lee, Le Phuc Thinh, Jean-Daniel Bancal, Alessandro Cere
We present a violation of the CHSH inequality without the fair sampling assumption with a continuously pumped photon pairs source combined with two high efficiency superconducting detectors. Due to the continuous nature of the source, the choice of the