Journal ArticleAdvanced Quantum Technologies · November 1, 2023
Parallel operations are important for both near-term quantum computers and larger-scale fault-tolerant machines because they reduce execution time and qubit idling. This study proposes and implements a pairwise-parallel gate scheme on a trapped-ion quantum ...
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Journal ArticlePhysical Review Research · April 1, 2023
Two-qubit gate performance is vital for scaling up ion-trap quantum computing. Optimized quantum control is needed to achieve reductions in gate duration and gate error rate. We describe two-qubit gates with addressed Raman beams within a linear trapped-io ...
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Journal ArticleQuantum Science and Technology · January 1, 2023
Combinatorial optimization problems on graphs have broad applications in science and engineering. The quantum approximate optimization algorithm (QAOA) is a method to solve these problems on a quantum computer by applying multiple rounds of variational cir ...
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Conference2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023 · January 1, 2023
Universal digital quantum computers are able to approximate any Hamiltonian evolution as a digital quantum circuit consisting of discrete time steps. Strongly interacting physics models, for example in high-energy physics or materials science, make this a ...
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Journal ArticleNature communications · November 2022
As we approach the era of quantum advantage, when quantum computers (QCs) can outperform any classical computer on particular tasks, there remains the difficult challenge of how to validate their performance. While algorithmic success can be easily verifie ...
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ConferenceProceedings of Science · July 8, 2022
We introduce a new method to calculate phase shifts on noisy intermediate scale quantum (NISQ) hardware platforms using a wave packet edge time delay. The method uses the early and intermediate stages of the collision because the standard method based on t ...
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Journal ArticlePhysical Review Research · July 1, 2022
We propose a set of Bell-type nonlocal games that can be used to prove an unconditional quantum advantage in an objective and hardware-agnostic manner. In these games, the circuit depth needed to prepare a cyclic cluster state and measure a subset of its P ...
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Journal ArticlePhysical Review X · July 1, 2022
By leveraging shared entanglement between a pair of qubits, one can teleport a quantum state from one particle to another. Recent advances have uncovered an intrinsically many-body generalization of quantum teleportation, with an elegant and surprising con ...
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Journal ArticlePRX Quantum · June 1, 2022
Tracking the dynamics of physical systems in real time is a prime application of quantum computers. Using a trapped-ion system with up to six qubits, we simulate the real-time dynamics of a lattice gauge theory in 1+1 dimensions, i.e., the lattice Schwinge ...
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Journal ArticlePhysical review letters · April 2022
Out-of-time-ordered correlators (OTOCs) are a key observable in a wide range of interconnected fields including many-body physics, quantum information science, and quantum gravity. Measuring OTOCs using near-term quantum simulators will extend our ability ...
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Journal ArticlePhysical Review A · February 1, 2022
Trapped ions form an advanced technology platform for quantum information processing with long qubit coherence times, high-fidelity quantum logic gates, optically active qubits, and a potential to scale up in size while preserving a high level of connectiv ...
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Journal ArticleQuantum · January 1, 2022
Periodically-driven systems are ubiquitous in science and technology. In quantum dynamics, even a small number of periodically-driven spins leads to complicated dynamics. Hence, it is of interest to understand what constraints such dynamics must satisfy. W ...
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Journal ArticleAdvanced Quantum Technologies · November 1, 2023
Parallel operations are important for both near-term quantum computers and larger-scale fault-tolerant machines because they reduce execution time and qubit idling. This study proposes and implements a pairwise-parallel gate scheme on a trapped-ion quantum ...
Full textCite
Journal ArticlePhysical Review Research · April 1, 2023
Two-qubit gate performance is vital for scaling up ion-trap quantum computing. Optimized quantum control is needed to achieve reductions in gate duration and gate error rate. We describe two-qubit gates with addressed Raman beams within a linear trapped-io ...
Full textCite
Journal ArticleQuantum Science and Technology · January 1, 2023
Combinatorial optimization problems on graphs have broad applications in science and engineering. The quantum approximate optimization algorithm (QAOA) is a method to solve these problems on a quantum computer by applying multiple rounds of variational cir ...
Full textCite
Conference2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023 · January 1, 2023
Universal digital quantum computers are able to approximate any Hamiltonian evolution as a digital quantum circuit consisting of discrete time steps. Strongly interacting physics models, for example in high-energy physics or materials science, make this a ...
Full textCite
Journal ArticleNature communications · November 2022
As we approach the era of quantum advantage, when quantum computers (QCs) can outperform any classical computer on particular tasks, there remains the difficult challenge of how to validate their performance. While algorithmic success can be easily verifie ...
Full textCite
ConferenceProceedings of Science · July 8, 2022
We introduce a new method to calculate phase shifts on noisy intermediate scale quantum (NISQ) hardware platforms using a wave packet edge time delay. The method uses the early and intermediate stages of the collision because the standard method based on t ...
Cite
Journal ArticlePhysical Review Research · July 1, 2022
We propose a set of Bell-type nonlocal games that can be used to prove an unconditional quantum advantage in an objective and hardware-agnostic manner. In these games, the circuit depth needed to prepare a cyclic cluster state and measure a subset of its P ...
Full textCite
Journal ArticlePhysical Review X · July 1, 2022
By leveraging shared entanglement between a pair of qubits, one can teleport a quantum state from one particle to another. Recent advances have uncovered an intrinsically many-body generalization of quantum teleportation, with an elegant and surprising con ...
Full textCite
Journal ArticlePRX Quantum · June 1, 2022
Tracking the dynamics of physical systems in real time is a prime application of quantum computers. Using a trapped-ion system with up to six qubits, we simulate the real-time dynamics of a lattice gauge theory in 1+1 dimensions, i.e., the lattice Schwinge ...
Full textCite
Journal ArticlePhysical review letters · April 2022
Out-of-time-ordered correlators (OTOCs) are a key observable in a wide range of interconnected fields including many-body physics, quantum information science, and quantum gravity. Measuring OTOCs using near-term quantum simulators will extend our ability ...
Full textCite
Journal ArticlePhysical Review A · February 1, 2022
Trapped ions form an advanced technology platform for quantum information processing with long qubit coherence times, high-fidelity quantum logic gates, optically active qubits, and a potential to scale up in size while preserving a high level of connectiv ...
Full textCite
Journal ArticleQuantum · January 1, 2022
Periodically-driven systems are ubiquitous in science and technology. In quantum dynamics, even a small number of periodically-driven spins leads to complicated dynamics. Hence, it is of interest to understand what constraints such dynamics must satisfy. W ...
Full textCite
Journal ArticlePhysical Review A · December 1, 2021
Quantum walks are a promising framework for developing quantum algorithms and quantum simulations. They represent an important test case for the application of quantum computers. Here we present different forms of discrete-time quantum walks (DTQWs) and sh ...
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Journal ArticlePhysical Review Research · December 1, 2021
Quantum field theories are the cornerstones of modern physics, providing relativistic and quantum mechanical descriptions of physical systems at the most fundamental level. Simulating real-time dynamics within these theories remains elusive in classical co ...
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Journal ArticlePhysical Review D · September 1, 2021
We present a method to extract the phase shift of a scattering process using the real-time evolution in the early and intermediate stages of the collision in order to estimate the time delay of a wave packet. This procedure is convenient when using noisy q ...
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Journal ArticlePhysical Review Applied · August 1, 2021
Fault-tolerant quantum error correction (QEC) is crucial for unlocking the true power of quantum computers. QEC codes use multiple physical qubits to encode a logical qubit, which is protected against errors at the physical qubit level. Here, we use a trap ...
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Journal ArticleScience advances · August 2021
Partition functions are ubiquitous in physics: They are important in determining the thermodynamic properties of many-body systems and in understanding their phase transitions. As shown by Lee and Yang, analytically continuing the partition function to the ...
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Journal ArticlePhysical review letters · June 2021
In order to scale up quantum processors and achieve a quantum advantage, it is crucial to economize on the power requirement of two-qubit gates, make them robust to drift in experimental parameters, and shorten the gate times. Applicable to all quantum com ...
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Journal ArticleReviews of Modern Physics · April 7, 2021
Laser-cooled and trapped atomic ions form an ideal standard for the simulation of interacting quantum spin models. Effective spins are represented by appropriate internal energy levels within each ion, and the spins can be measured with near-perfect effici ...
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Journal ArticlePhysical Review A · March 1, 2021
A disordered quantum system of interacting particles exhibits localized behavior when the disorder is large compared to the interaction strength. Studying this phenomenon on a quantum computer with no, or limited, error correction is challenging because ev ...
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Journal ArticleJournal of immunology (Baltimore, Md. : 1950) · December 2020
Mutations in two genes can result in activated PI3Kδ syndrome (APDS), a rare immunodeficiency disease with limited therapeutic options. Seletalisib, a potent, selective PI3Kδ inhibitor, was evaluated in patients with APDS1 and APDS2. In the phase 1b study ...
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Journal ArticleProceedings of the National Academy of Sciences of the United States of America · October 2020
Finite-temperature phases of many-body quantum systems are fundamental to phenomena ranging from condensed-matter physics to cosmology, yet they are generally difficult to simulate. Using an ion trap quantum computer and protocols motivated by the quantum ...
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Journal ArticleNature communications · July 2020
The quantum walk formalism is a widely used and highly successful framework for modeling quantum systems, such as simulations of the Dirac equation, different dynamics in both the low and high energy regime, and for developing a wide range of quantum algor ...
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Journal ArticlePhysik in unserer Zeit · July 2020
ZusammenfassungQuantencomputer versprechen, spezielle, für Anwendungen hochinteressante Aufgaben zu lösen. An diesen NP‐harten Problemen scheitern herkömmliche Supercomputer. Eine Technik, die intensiv erforscht wird, ist d ...
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Journal ArticleIEEE Micro · May 1, 2020
Current quantum computers have very different qubit implementations, instruction sets, qubit connectivity, and noise characteristics. Using real-system evaluations on seven quantum systems from three leading vendors, our work explores fundamental design qu ...
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Journal ArticlePhysical Review A · December 16, 2019
We report results for simulating an effective field theory to compute the binding energy of the deuteron nucleus using a hybrid algorithm on a trapped-ion quantum computer. Two increasingly complex unitary coupled-cluster ansatze have been used to compute ...
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Journal ArticleScience advances · October 2019
Generative modeling is a flavor of machine learning with applications ranging from computer vision to chemical design. It is expected to be one of the techniques most suited to take advantage of the additional resources provided by near-term quantum comput ...
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Journal ArticlePhysical Review A · August 26, 2019
Ion trap quantum computers are based on modulating the Coulomb interaction between atomic ion qubits using external forces. However, the spectral crowding of collective motional modes could pose a challenge to the control of such interactions for large num ...
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Journal ArticleNature · August 2019
The circuit model of a quantum computer consists of sequences of gate operations between quantum bits (qubits), drawn from a universal family of discrete operations1. The ability to execute parallel entangling quantum gates offers efficiency gai ...
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ConferenceProceedings - International Symposium on Computer Architecture · June 22, 2019
In recent years, Quantum Computing (QC) has progressed to the point where small working prototypes are available for use. Termed Noisy Intermediate-Scale Quantum (NISQ) computers, these prototypes are too small for large benchmarks or even for Quantum Erro ...
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Journal ArticlePhysical Review A · April 30, 2019
We propose a measurement scheme that validates the preparation of an n-qubit stabilizer state. The scheme involves a measurement of n Pauli observables, a priori determined from the stabilizer state and which can be realized using single-qubit gates. Based ...
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Journal ArticleNature · March 2019
Quantum scrambling is the dispersal of local information into many-body quantum entanglements and correlations distributed throughout an entire system. This concept accompanies the dynamics of thermalization in closed quantum systems, and has recently emer ...
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ConferenceOptics InfoBase Conference Papers · January 1, 2019
I will review some of the latest results in both gate-based quantum computing and analog quantum simulation, speculating on how this platform can realistically be scaled in the near future. ...
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Journal ArticlePhysical Review A · November 26, 2018
The efficient simulation of correlated quantum systems is a promising near-term application of quantum computers. Here, we present a measurement of the second Rényi entropy of the ground state of the two-site Fermi-Hubbard model on a five-qubit programmabl ...
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Journal ArticleJournal of Physics B: Atomic, Molecular and Optical Physics · August 17, 2018
We reduce measurement errors in a quantum computer using machine learning techniques. We exploit a simple yet versatile neural network to classify multi-qubit quantum states, which is trained using experimental data. This flexible approach allows the incor ...
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Journal ArticleQuantum Science and Technology · July 10, 2018
We demonstrate a Bayesian quantum game on an ion-trap quantum computer with five qubits. The players share an entangled pair of qubits and perform rotations on their qubit as the strategy choice. Two five-qubit circuits are sufficient to run all 16 possibl ...
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Journal ArticlePhysical review letters · February 2018
The local phonon modes in a Coulomb crystal of trapped ions can represent a Hubbard system of coupled bosons. We selectively prepare single excitations at each site and observe free hopping of a boson between sites, mediated by the long-range Coulomb inter ...
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Journal ArticlePhysical review letters · January 2018
In an ion trap quantum computer, collective motional modes are used to entangle two or more qubits in order to execute multiqubit logical gates. Any residual entanglement between the internal and motional states of the ions results in loss of fidelity, esp ...
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Journal ArticleNature communications · December 2017
The Grover quantum search algorithm is a hallmark application of a quantum computer with a well-known speedup over classical searches of an unsorted database. Here, we report results for a complete three-qubit Grover search algorithm using the scalable qua ...
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Journal ArticleScience advances · October 2017
Quantum computers will eventually reach a size at which quantum error correction becomes imperative. Quantum information can be protected from qubit imperfections and flawed control operations by encoding a single logical qubit in multiple physical qubits. ...
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Journal ArticleProceedings of the National Academy of Sciences of the United States of America · March 2017
We run a selection of algorithms on two state-of-the-art 5-qubit quantum computers that are based on different technology platforms. One is a publicly accessible superconducting transmon device (www.Researchibm.com/ibm-q) with limited connectivity ...
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Journal ArticlePhysical Review A · February 27, 2017
Individual addressing of qubits is essential for scalable quantum computation. Spatial addressing allows unlimited numbers of qubits to share the same frequency, while enabling arbitrary parallel operations. We demonstrate addressing of long-lived Ca+43 "a ...
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Journal ArticleNature · August 2016
Quantum computers can solve certain problems more efficiently than any possible conventional computer. Small quantum algorithms have been demonstrated on multiple quantum computing platforms, many specifically tailored in hardware to implement a particular ...
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Journal ArticlePhysical review letters · August 2016
We demonstrate laser-driven two-qubit and single-qubit logic gates with respective fidelities 99.9(1)% and 99.9934(3)%, significantly above the ≈99% minimum threshold level required for fault-tolerant quantum computation, using qubits stored in hyperfine g ...
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Journal ArticleNature · December 2015
Entanglement is one of the most fundamental properties of quantum mechanics, and is the key resource for quantum information processing (QIP). Bipartite entangled states of identical particles have been generated and studied in several experiments, and pos ...
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Journal ArticlePhysical review letters · November 2014
We implement all single-qubit operations with fidelities significantly above the minimum threshold required for fault-tolerant quantum computing, using a trapped-ion qubit stored in hyperfine "atomic clock" states of ^{43}Ca^{+}. We measure a combined qubi ...
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Journal ArticleApplied Physics B: Lasers and Optics · January 1, 2014
We propose a surface ion trap design incorporating microwave control electrodes for near-field single-qubit control. The electrodes are arranged so as to provide arbitrary frequency, amplitude and polarization control of the microwave field in one trap zon ...
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Journal ArticleOptics letters · December 2013
We describe the injection locking of two infrared (794 nm) laser diodes that are each part of a frequency-doubled laser system. An acousto-optic modulator in the injection path gives an offset of 1.6 GHz between the lasers for driving Raman transitions bet ...
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Journal ArticleApplied Physics Letters · January 28, 2013
We describe the design, fabrication, and testing of a surface-electrode ion trap, which incorporates microwave waveguides, resonators, and coupling elements for the manipulation of trapped ion qubits using near-field microwaves. The trap is optimised to gi ...
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Journal ArticleApplied Physics B: Lasers and Optics · June 1, 2012
We demonstrate a Doppler cooling and detection scheme for ions with low-lying D levels which almost entirely suppresses scattered laser light background, while retaining a high fluorescence signal and efficient cooling. We cool a single ion with a laser on ...
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Journal ArticleApplied Physics B: Lasers and Optics · June 1, 2012
We characterise the performance of a surfaceelectrode ion "chip" trap fabricated using established semiconductor integrated circuit and micro-electro-mechanicalsystem (MEMS) microfabrication processes, which are in principle scalable to much larger ion tra ...
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Journal ArticleNew Journal of Physics · May 17, 2010
We describe a new electrode design for a surface-electrode Paul trap, which allows rotation of the normal modes out of the trap plane, and a technique for micromotion compensation in all directions using a two-photon process, which avoids the need for an u ...
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Journal ArticleJournal of Modern Optics · October 1, 2009
Using a segmented ion trap with mK laser-cooled ions we have realised a novel single ion source which can deterministically deliver a wide range of ion species, isotopes or ionic molecules [Schnitzler et al. Phys. Rev. Lett. 2009, 102, 070501]. Experimenta ...
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Journal ArticlePhysical review letters · February 2009
The major challenges to fabricate quantum processors and future nano-solid-state devices are material modification techniques with nanometer resolution and suppression of statistical fluctuations of dopants or qubit carriers. Based on a segmented ion trap ...
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