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Search Publications by: Emanuel Knill (Fed)

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Displaying 1 - 25 of 91

Multi-mode Gaussian State Analysis with Total Photon Counting

July 11, 2023
Author(s)
Arik Avagyan, Scott Glancy, Emanuel Knill
The continuing improvement in the qualities of photon-number-resolving (PNR) detectors opens new possibilities for measuring quantum states of light. In this work we consider the question of what properties of an arbitrary multi-mode Gaussian state are

Constraints on Gaussian Error Channels and Measurements for Quantum Communication

April 10, 2023
Author(s)
Alexander T. Kwiatkowski, Ezad Shojaee, Sristy Agrawal, Akira Kyle, Curtis Rau, Scott Glancy, Emanuel Knill
Joint Gaussian measurements of two quantum systems are important for quantum communication between remote parties and are often used in continuous-variable teleportation or entanglement-swapping protocols. Many of the errors in real-world implementations

Improving quantum state detection with adaptive sequential observations

May 13, 2022
Author(s)
Emanuel Knill, Scott Glancy, Daniel Cole, Shawn Geller
For many quantum systems intended for information processing, one detects the logical state of a qubit by integrating a continuously observed quantity over time. For example, ion and atom qubits are typically measured by driving a cycling transition and

High-fidelity indirect readout of trapped-ion hyperfine qubits

April 21, 2022
Author(s)
Stephen Erickson, Jenny Wu, Panyu Hou, Daniel Cole, Shawn Geller, Alexander Kwiatkowski, Scott Glancy, Emanuel Knill, Daniel Slichter, Andrew C. Wilson, Dietrich Leibfried
We propose and demonstrate a protocol for high-fidelity indirect readout of trapped ion hyperfine qubits, where the state of a 9Be+ qubit ion is mapped to a 25Mg+ readout ion using laser-driven Raman transitions. By partitioning the 9Be+ ground-state

Multiphoton quantum metrology with neither pre- nor post-selected measurements

October 21, 2021
Author(s)
Chenglong You, Mingyuan Hong, Peter Bierhorst, Adriana Lita, Scott Glancy, Steven Kolthammer, Emanuel Knill, Sae Woo Nam, Richard Mirin, Omar Magana-Loaiza, Thomas Gerrits
The quantum statistical fluctuations of the electromagnetic field establish fundamental limits on the sensitivity of optical measurements. This fundamental limit, known as the shot-noise limit, imposes constraints on classical technologies, which can be

High-fidelity laser-free universal control of trapped ion qubits

September 8, 2021
Author(s)
Raghavendra Srinivas, Emanuel Knill, Robert Sutherland, Alexander T. Kwiatkowski, Hannah M. Knaack, Scott Glancy, David J. Wineland, Shaun C. Burd, Dietrich Leibfried, Andrew C. Wilson, David T. Allcock, Daniel Slichter
Universal control of multiple qubits—the ability to entangle qubits and to perform arbitrary individual qubit operations—is a fundamental resource for quantum computing, simulation and networking. Qubits realized in trapped atomic ions have shown the

Quantum Randomness from Probability Estimation with Classical Side Information

September 22, 2020
Author(s)
Emanuel 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

Certified Quantum Measurement of Majorana Fermions

March 12, 2020
Author(s)
Emanuel H. Knill, Abu Ashik Md. Irfan, Karl H. Mayer, Gerardo Ortiz
We present a quantum self-testing protocol to certify measurements of fermion parity involving Majorana fermion modes. We show that observing a set of ideal measurement statistics implies anticommutativity of the implemented Majorana fermion parity

Experimental Low-Latency Device-Independent Quantum Randomness

January 10, 2020
Author(s)
Yanbao Zhang, Lynden K. Shalm, Joshua C. Bienfang, Martin J. Stevens, Michael D. Mazurek, Sae Woo Nam, Carlos Abellan, Waldimar Amaya, Morgan Mitchell, Honghao Fu, Carl A. Miller, Alan Mink, Emanuel H. Knill
Applications of randomness such as private key generation and public randomness beacons require small blocks of certified random bits on demand. Device-independent quantum randomness can produce such random bits, but existing quantum-proof protocols and

Efficient Randomness Certification by Quantum Probability Estimation

January 7, 2020
Author(s)
Emanuel H. Knill, Yanbao Zhang, Honghao Fu
For practical applications of quantum randomness generation, it is important to produce a fixed block of fresh random bits with as few trials as possible. Consequently, protocols with high finite-data are preferred. In this work we develop a broadly

Quantum gate teleportation between separated zones of a trapped-ion processor

May 31, 2019
Author(s)
Yong Wan, Daniel Kienzler, Stephen D. Erickson, Karl H. Mayer, Ting R. Tan, Jenny J. Wu, Hilma H. Macedo De Vasconcelos, Scott C. Glancy, Emanuel H. Knill, David J. Wineland, Andrew C. Wilson, Dietrich G. Leibfried
Large-scale quantum computers will inevitably require quantum gate operations between widely separated qubits, even within a single quantum information processing device. Nearly two decades ago, Gottesman and Chuang proposed a method for implementing such

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