scholarly journals Elucidating reaction mechanisms on quantum computers

2017 ◽  
Vol 114 (29) ◽  
pp. 7555-7560 ◽  
Author(s):  
Markus Reiher ◽  
Nathan Wiebe ◽  
Krysta M. Svore ◽  
Dave Wecker ◽  
Matthias Troyer
Keyword(s):  
Reaction Mechanisms ◽  
Quantum Computer ◽  
Quantum Error Correction ◽  
Quantum Computers ◽  
Chemical Systems ◽  
Small Quantum ◽  
Quantum Technology ◽  
Classical Computer ◽  
Quantum Error ◽  
Biological Nitrogen

With rapid recent advances in quantum technology, we are close to the threshold of quantum devices whose computational powers can exceed those of classical supercomputers. Here, we show that a quantum computer can be used to elucidate reaction mechanisms in complex chemical systems, using the open problem of biological nitrogen fixation in nitrogenase as an example. We discuss how quantum computers can augment classical computer simulations used to probe these reaction mechanisms, to significantly increase their accuracy and enable hitherto intractable simulations. Our resource estimates show that, even when taking into account the substantial overhead of quantum error correction, and the need to compile into discrete gate sets, the necessary computations can be performed in reasonable time on small quantum computers. Our results demonstrate that quantum computers will be able to tackle important problems in chemistry without requiring exorbitant resources.

scholarly journals Superconducting Qubits: Current State of Play

2020 ◽  
Vol 11 (1) ◽  
pp. 369-395 ◽  
Author(s):  
Morten Kjaergaard ◽  
Mollie E. Schwartz ◽  
Jochen Braumüller ◽  
Philip Krantz ◽  
Joel I.-J. Wang ◽  
...  
Keyword(s):  
Quantum Computer ◽  
Quantum Algorithms ◽  
Quantum Error Correction ◽  
Superconducting Qubits ◽  
Quantum Computers ◽  
Superconducting Qubit ◽  
Current State ◽  
Scale Error ◽  
Logical Qubits ◽  
Quantum Error

Superconducting qubits are leading candidates in the race to build a quantum computer capable of realizing computations beyond the reach of modern supercomputers. The superconducting qubit modality has been used to demonstrate prototype algorithms in the noisy intermediate-scale quantum (NISQ) technology era, in which non-error-corrected qubits are used to implement quantum simulations and quantum algorithms. With the recent demonstrations of multiple high-fidelity, two-qubit gates as well as operations on logical qubits in extensible superconducting qubit systems, this modality also holds promise for the longer-term goal of building larger-scale error-corrected quantum computers. In this brief review, we discuss several of the recent experimental advances in qubit hardware, gate implementations, readout capabilities, early NISQ algorithm implementations, and quantum error correction using superconducting qubits. Although continued work on many aspects of this technology is certainly necessary, the pace of both conceptual and technical progress in recent years has been impressive, and here we hope to convey the excitement stemming from this progress.

scholarly journals Decoherence dynamics estimation for superconducting gate-model quantum computers

2020 ◽  
Vol 19 (10) ◽  
Author(s):  
Laszlo Gyongyosi
Keyword(s):  
Gaussian Noise ◽  
Quantum Computer ◽  
Computer Architectures ◽  
Quantum Circuits ◽  
Optimal Placement ◽  
Quantum Computers ◽  
Intermediate Scale ◽  
Layout Generation ◽  
Quantum Technology ◽  
Physical Layout

Abstract Superconducting gate-model quantum computer architectures provide an implementable model for practical quantum computations in the NISQ (noisy intermediate scale quantum) technology era. Due to hardware restrictions and decoherence, generating the physical layout of the quantum circuits of a gate-model quantum computer is a challenge. Here, we define a method for layout generation with a decoherence dynamics estimation in superconducting gate-model quantum computers. We propose an algorithm for the optimal placement of the quantum computational blocks of gate-model quantum circuits. We study the effects of capacitance interference on the distribution of the Gaussian noise in the Josephson energy.

Fluxon-controlled quantum computer

2016 ◽  
Vol 14 (07) ◽  
pp. 1650040
Author(s):  
Toshiyuki Fujii ◽  
Shigemasa Matsuo ◽  
Noriyuki Hatakenaka
Keyword(s):  
Error Correction ◽  
Quantum Computer ◽  
Quantum Error Correction ◽  
Capacitively Coupled ◽  
Swap Gate ◽  
Flux Qubits ◽  
Superconducting Flux Qubits ◽  
Quantum Error ◽  
At Home

We propose a fluxon-controlled quantum computer incorporated with three-qubit quantum error correction using special gate operations, i.e. joint-phase and SWAP gate operations, inherent in capacitively coupled superconducting flux qubits. The proposed quantum computer acts exactly like a knitting machine at home.

The Realization of New Computing Model and System Research Related to Quantum Computer

2014 ◽  
Vol 1078 ◽  
pp. 413-416
Author(s):  
Hai Yan Liu
Keyword(s):  
Quantum Computing ◽  
High Performance ◽  
Quantum Physics ◽  
Quantum Computer ◽  
Quantum Computers ◽  
Information Coding ◽  
Computing Model ◽  
Mechanics Model ◽  
Electronic Spin ◽  
Classical Computer

The ultimate goal of quantum calculation is to build high performance practical quantum computers. With quantum mechanics model of computer information coding and computational principle, it is proved in theory to be able to simulate the classical computer is currently completely, and with more classical computer, quantum computation is one of the most popular fields in physics research in recent ten years, has formed a set of quantum physics, mathematics. This paper to electronic spin doped fullerene quantum aided calculation scheme, we through the comprehensive use of logic based network and based on the overall control of the two kinds of quantum computing model, solve the addressing problem of nuclear spin, avoids the technical difficulties of pre-existing. We expect the final realization of the quantum computer will depend on the integrated use of in a variety of quantum computing model and physical realization system, and our primary work shows this feature..

Assembly of a Coreset of Earth Observation Images on a Small Quantum Computer

Electronics ◽  
2021 ◽  
Vol 10 (20) ◽  
pp. 2482
Author(s):  
Soronzonbold Otgonbaatar ◽  
Mihai Datcu
Keyword(s):  
Hyperspectral Image ◽  
Quantum Computer ◽  
Synthetic Data ◽  
Quantum Computers ◽  
Kl Divergence ◽  
Original Dataset ◽  
Small Quantum ◽  
Conventional Computer ◽  
D Wave ◽  
Iris Data

Satellite instruments monitor the Earth’s surface day and night, and, as a result, the size of Earth observation (EO) data is dramatically increasing. Machine Learning (ML) techniques are employed routinely to analyze and process these big EO data, and one well-known ML technique is a Support Vector Machine (SVM). An SVM poses a quadratic programming problem, and quantum computers including quantum annealers (QA) as well as gate-based quantum computers promise to solve an SVM more efficiently than a conventional computer; training the SVM by employing a quantum computer/conventional computer represents a quantum SVM (qSVM)/classical SVM (cSVM) application. However, quantum computers cannot tackle many practical EO problems by using a qSVM due to their very low number of input qubits. Hence, we assembled a coreset (“core of a dataset”) of given EO data for training a weighted SVM on a small quantum computer, a D-Wave quantum annealer with around 5000 input quantum bits. The coreset is a small, representative weighted subset of an original dataset, and its performance can be analyzed by using the proposed weighted SVM on a small quantum computer in contrast to the original dataset. As practical data, we use synthetic data, Iris data, a Hyperspectral Image (HSI) of Indian Pine, and a Polarimetric Synthetic Aperture Radar (PolSAR) image of San Francisco. We measured the closeness between an original dataset and its coreset by employing a Kullback–Leibler (KL) divergence test, and, in addition, we trained a weighted SVM on our coreset data by using both a D-Wave quantum annealer (D-Wave QA) and a conventional computer. Our findings show that the coreset approximates the original dataset with very small KL divergence (smaller is better), and the weighted qSVM even outperforms the weighted cSVM on the coresets for a few instances of our experiments. As a side result (or a by-product result), we also present our KL divergence findings for demonstrating the closeness between our original data (i.e., our synthetic data, Iris data, hyperspectral image, and PolSAR image) and the assembled coreset.

Performance of topological quantum error correction in the presence of correlated noise

2018 ◽  
Vol 18 (9&10) ◽  
pp. 743-778
Author(s):  
Muhammad Ahsan ◽  
Syed Abbas Zilqurnain Naqvi
Keyword(s):  
Error Correction ◽  
Noise Level ◽  
Quantum Computer ◽  
Quantum Error Correction ◽  
Noise Model ◽  
Correlated Noise ◽  
Computational Accuracy ◽  
Topological Quantum ◽  
Large Numbers ◽  
Quantum Error

We investigate the efficacy of topological quantum error-correction in correlated noise model which permits collective coupling of all the codeword qubits to the same non-Markovian environment. In this noise model, the probability distribution over set of phase-flipped qubits, decays sub-exponentially in the size of the set and carries non-trivial likelihood of the occurring large numbers of qubits errors. We find that in the presence of noise correlation, one cannot guarantee arbitrary high computational accuracy simply by incrementing the codeword size while retaining constant noise level per qubit operation. However, if instead, per-operation qubit error probability in an n-qubits long codeword is reduced O(\sqrt{n}) times below the accuracy threshold, arbitrarily accurate quantum computation becomes feasible with acceptable scaling of the codeword size. Our results suggest that progressively reducing noise level in qubits and gates is as important as continuously integrating more qubits to realize scalable and reliable quantum computer.

scholarly journals Accelerating quantum computer developments

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Garrelt J. N. Alberts ◽  
M. Adriaan Rol ◽  
Thorsten Last ◽  
Benno W. Broer ◽  
Cornelis C. Bultink ◽  
...  
Keyword(s):  
Supply Chain ◽  
Product Development ◽  
High Performance ◽  
Quantum Computer ◽  
Building Blocks ◽  
High Tech ◽  
Quantum Computers ◽  
Link Type ◽  
Development Approach ◽  
Quantum Technology

Abstract Product development Given the recent breakthroughs in quantum technology development in R& D labs all over the world, the perspective of high-tech companies has changed. Product development is initiated next to the existing research and technology development activities. Quantum computer product roadmap Considering the quantum computer as a product requires standardization and integration of all its building blocks and a mature supply chain that can provide high-quality components and can ensure security of supply. The product development approach puts focus on functionality and performance requirements of the product and uses state-of-the-art technology to build the product. Based on the expected requirements of future products it is possible to outline a product development roadmap. It is expected that a fully functional quantum computer will be available within a decade from now, and will be used by the High Performance Computing (HPC) market, where it will replace (part of) the supercomputers that are currently used for complex calculations and data management. In the short term, a partly functional quantum computer will be available and of interest to the R&D market, which has a need for such a product to expedite their quantum technology developments. ImpaQT project In this paper, we present the product development approach and roadmap for quantum computers, based on superconducting circuits as an example. A group of companies in the Dutch quantum ecosystem (Quantum Delta) have joined forces and have started the ImpaQT project. The companies of the ImpaQT consortium form a local supply chain for key components of quantum computers. This paper shows that quantum community has reached the next level of maturity and that the quantum computer as a commercial product looks set to become a reality.

TYPE-II QUANTUM COMPUTERS

2001 ◽  
Vol 12 (09) ◽  
pp. 1273-1284 ◽  
Author(s):  
JEFFREY YEPEZ
Keyword(s):  
Short Range ◽  
Quantum Computer ◽  
Quantum Mechanical ◽  
Quantum Computers ◽  
Type Ii ◽  
Computational Power ◽  
Classical Communication ◽  
Small Quantum ◽  
Short Time ◽  
Quantum Parallelism

This paper discusses a computing architecture that uses both classical parallelism and quantum parallelism. We consider a large parallel array of small quantum computers, connected together by classical communication channels. This kind of computer is called a type-II quantum computer, to differentiate it from a globally phase-coherent quantum computer, which is the first type of quantum computer that has received nearly exclusive attention in the literature. Although a hybrid, a type-II quantum computer retains the crucial advantage allowed by quantum mechanical superposition that its computational power grows exponentially in the number of phase-coherent qubits per node, only short-range and short time phase-coherence is needed, which significantly reduces the level of engineering facility required to achieve its construction. Therefore, the primary factor limiting its computational power is an economic one and not a technological one, since the volume of its computational medium can in principle scale indefinitely.

scholarly journals Quantum Computing Concepts with Deutsch Jozsa Algorithm

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Poornima Aradyamath ◽  
Naghabhushana N M ◽  
Rohitha Ujjinimatad
Keyword(s):  
Fourier Transform ◽  
Quantum Computing ◽  
Quantum Computation ◽  
Mathematical Description ◽  
Quantum Computer ◽  
Quantum Algorithms ◽  
Quantum Computers ◽  
Quantum Fourier Transform ◽  
Basic Concepts ◽  
Classical Computer

In this paper, we briefly review the basic concepts of quantum computation,  entanglement,  quantum cryptography and quantum fourier  transform.   Quantum algorithms like Deutsch Jozsa, Shor’s   factorization and Grover’s data search are developed using fourier  transform  and quantum computation concepts to build quantum computers.  Researchers are finding a way to build quantum computer that works more efficiently than classical computer.  Among the  standard well known  algorithms  in the field of quantum computation  and communication we  describe  mathematically Deutsch Jozsa algorithm  in detail for  2  and 3 qubits.  Calculation of balanced and unbalanced states is shown in the mathematical description of the algorithm.

Quantum Error Correction

2006 ◽  
Author(s):  
Phillip Kaye ◽  
Raymond Laflamme ◽  
Michele Mosca
Keyword(s):  
Error Correction ◽  
Large Scale ◽  
Success Probability ◽  
Error Recovery ◽  
Error Correcting Codes ◽  
Quantum Error Correction ◽  
Quantum Computers ◽  
Model Of Computation ◽  
Limited Precision ◽  
Quantum Error

A mathematical model of computation is an idealized abstraction. We design algorithms and perform analysis on the assumption that the mathematical operations we specify will be carried out exactly, and without error. Physical devices that implement an abstract model of computation are imperfect and of limited precision. For example, when a digital circuit is implemented on a physical circuit board, unwanted electrical noise in the environment may cause components to behave differently than expected, and may cause voltage levels (bit-values) to change. These sources of error must be controlled or compensated for, or else the resulting loss of efficiency may reduce the power of the information-processing device. If individual steps in a computation succeed with probability p, then a computation involving t sequential steps will have a success probability that decreases exponentially as pt. Although it may be impossible to eliminate the sources of errors, we can devise schemes to allow us to recover from errors using a reasonable amount of additional resources. Many classical digital computing devices use error-correcting codes to perform detection of and recovery from errors. The theory of error-correcting codes is itself a mathematical abstraction, but it is one that explicitly accounts for errors introduced by the imperfection and imprecision of realistic devices. This theory has proven extremely effective in allowing engineers to build computing devices that are resilient against errors. Quantum computers are more susceptible to errors than classical digital computers, because quantum mechanical systems are more delicate and more difficult to control. If large-scale quantum computers are to be possible, a theory of quantum error correction is needed. The discovery of quantum error correction has given researchers confidence that realistic large-scale quantum computing devices can be built despite the presence of errors. We begin by considering fundamental concepts for error correction in a classical setting. We will focus on three of these concepts: (a) the characterization of the error model, (b) the introduction of redundancy through encoding, and (c) an error recovery procedure. We will later see that these concepts generalize quite naturally for quantum error correction.

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