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Search Publications by: Emanuel Knill (Fed)

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Displaying 26 - 50 of 182

Quantum Process Fidelity Bounds from Sets of Input States

November 21, 2018
Author(s)
Emanuel H. Knill, Karl H. Mayer
We investigate the problem of bounding the quantum process fidelity given bounds on the fidelities between target states and the action of a process on a set of pure input states. We formulate the problem as a semidefinite program and prove convexity of

Certifying Quantum Randomness by Probability Estimation

October 31, 2018
Author(s)
Emanuel H. Knill, Yanbao Zhang, Peter L. Bierhorst
We introduce probability estimation, a broadly applicable frameworkto certify randomness in a finite sequence of measurements subject to verifiable physical constraints and with respect to classical side information. Examples include randomness from single

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

Quantum Probability Estimation for Randomness with Quantum Side Information

June 12, 2018
Author(s)
Emanuel H. Knill, yanbao zhang, Honghao Fu
We develop a quantum version of the probability estimation framework [arXiv:1709.06159] for randomness generation with quantum side information. We show that most of the properties of probability estimation hold for quantum probability estimation (QPE)

Experimentally Generated Random Numbers Certified by the Impossibility of Superluminal Signaling

April 11, 2018
Author(s)
Peter L. Bierhorst, Emanuel H. Knill, Scott C. Glancy, Yanbao Zhang, Alan Mink, Stephen P. Jordan, Andrea Rommal, Yi-Kai Liu, Bradley Christensen, Sae Woo Nam, Martin J. Stevens, Lynden K. Shalm
From dice to modern complex circuits, there have been many attempts to build increasingly better devices to generate random numbers. Today, randomness is fundamental to security and cryptographic systems, as well as safeguarding privacy. A key challenge

Quantum Estimation of the Classical Gravitational Field

November 6, 2017
Author(s)
Emanuel H. Knill, T. G. Downes, G. J. Milburn, C. M. Caves, J. R. van Meter
Here we describe a quantum limit to measurement of the classical gravitational field. Specifically, we formulate the quantum Cramer-Rao lower bound for estimating the single parameter in any one- parameter family of spacetime metrics. We employ the locally

Quantum Randomness from Probability Estimation with Classical Side Information

September 20, 2017
Author(s)
Emanuel H. Knill, Yanbao Zhang, Peter L. Bierhorst
We develop a framework for certifying randomness from Bell test trials based on directly estimating the probability of the measurement outcomes with adaptive test supermartingales. The number of trials need not be predetermined, and one can stop performing

Chained Bell inequality experiment with high-efficiency measurements

March 28, 2017
Author(s)
Ting Rei Tan, Stephen D. Erickson, Peter L. Bierhorst, Daniel Kienzler, Scott C. Glancy, Emanuel H. Knill, Dietrich G. Leibfried, David J. Wineland, Yong Wan
We report correlation measurements on two 9Be+ ions that violate a chained Bell inequality obeyed by any local-realistic theory. The correlations can be modeled as derived from a mixture of a local-realistic probabilistic distribution and a distribution

Preparation of entangled states through Hilbert space engineering

September 28, 2016
Author(s)
Yiheng Lin, John P. Gaebler, Florentin Reiter, Ting R. Tan, Ryan S. Bowler, Yong Wan, Adam C. Keith, Emanuel Knill, Kevin Coakley, Dietrich Leibfried, David J. Wineland, Scott Glancy
Entangled states are a crucial resource for quantum-based technologies such as quantum computers and quantum communication systems. Exploring new methods for entanglement generation is important for diversifying and eventually improving current approaches

High Fidelity Universal Gate Set for 9Be+ Ion Qubits

August 4, 2016
Author(s)
John P. Gaebler, Ting R. Tan, Yong Wan, Yiheng Lin, Ryan S. Bowler, Adam C. Keith, Scott Glancy, Kevin Coakley, Emanuel Knill, Dietrich Leibfried, David J. Wineland
We report high-fidelity laser-beam-induced quantum logic gates on qubits comprised of hyperfine states in 9Be+ ions, achieved in part through a combination of improved laser beam quality and control and improved state preparation. We demonstrate single

A strong loophole-free test of local realism

December 16, 2015
Author(s)
Lynden K. Shalm, Evan Meyer-Scott, B. G. Christensen, Peter L. Bierhorst, Michael A. Wayne, Deny Hamel, Martin J. Stevens, Thomas Gerrits, Scott C. Glancy, Michael S. Allman, Kevin J. Coakley, Shellee D. Dyer, Adriana E. Lita, Varun B. Verma, Joshua C. Bienfang, Alan L. Migdall, Yanbao Zhang, William Farr, Francesco Marsili, Matthew D. Shaw, Jeffrey Stern, Carlos Abellan, Waldimar Amaya, Valerio Pruneri, Thomas Jennewein, Morgan Mitchell, P. G. Kwiat, Richard P. Mirin, Emanuel H. Knill, Sae Woo Nam
We present a loophole-free violation of local realism using entangled photon pairs. We ensure that all relevant events in our Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high