Demonstration of Fidelity Improvement Using Dynamical Decoupling with Superconducting Qubits

We use quantum detector tomography to characterize the qubit readout in terms of measurement POVMs on IBM Quantum Computers IBM Q 5 Tenerife and IBM Q 5 Yorktown. Our results suggest that the characterized detector model deviates from the ideal projectors by a few percent. Further improvement on this characterization can be made by adopting two-or more-qubit detector models instead of independent single-qubit detectors for all the qubits in one device. An unexpected behavior was seen in the physical qubit labelled as qubit 3 of IBM Q 5 Tenerife, which can be a consequence of detector crosstalk or qubit operations influencing each other and requires further investigation. This peculiar behavior is consistent with characterization from the more sophisticated approach of the gate set tomography. We also discuss how the characterized detectors' POVM, despite deviation from the ideal projectors, can be used to estimate the ideal detection distribution.

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“…on IBM Q Experience or Rigetti Computing, but some useful information was listed in the Appendix of Ref. [26]). Quantum Process Tomography (QPT).…”

Section: Tomographic Tools For States Detectors and Processesmentioning

confidence: 99%

Detector tomography on IBM quantum computers and mitigation of an imperfect measurement

et al. 2019

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“…An error correction technique that has been investigated in systems involving NV centres is dynamical decoupling [38][39][40] , which decouples the system from its environmental degrees of freedom. We look at this method in more depth and in specific cases in the supplementary information.…”

Section: As Shown Inmentioning

confidence: 99%

Experimental simulation of hybrid quantum systems and entanglement on a quantum computer

Mazhandu

Mathieson

Coleman

et al. 2019

Applied Physics Letters

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We propose the utilization of the IBM Quantum Experience quantum computing system to simulate different scenarios involving common hybrid quantum system components, the Nitrogen Vacancy Centre (NV centre) and the Flux Qubit. We perform a series of the simulation experiments and demonstrate properties of a virtual hybrid system, including its spin relaxation rate and state coherence. In correspondence with experimental investigations we look at the scalability of such systems and show that increasing the number of coupled NV centres decreases the coherence time. We also establish the main error rate as a function of the number of control pulses in evaluating the fidelity of the four qubit virtual circuit with the simulator. Our results show that the virtual system can attain decoherence and fidelity values comparable to what has been reported for experimental investigations of similar physical hybrid systems, observing a coherence time at 0.35 s for a single NV centre qubit and fidelity in the range of 0.82. The work thus establishes an effective simulation test protocol for different technologies to test and analyze them before experimental investigations or as a supplementary measure.Quantum computers have the potential to solve problems that scale up at polynomial time and are thus predicted to outperform classical computers in a wide range of tasks including machine learning 1 , complex simulations 2-14 and optimization problems 15 . However, to establish true quantum supremacy, there is a need to build and demonstrate universal fault tolerant and scalable computing systems that can extend beyond the capabilities of classical computational systems 16 . To accomplish this several different types of systems and architectures have been proposed and continue to be studied. More recently this has included the demonstration of hybrid systems which combine different complementary quantum device elements, often coupling a combination of a superconducting, atomic and or spin systems into a single circuit 17,18 . NV centres have been studied extensively for this purpose, this is because the spin states associated with the NV centre present a well-studied energy level splitting which can be readily accessed and addressed through both electrical and optical measurement techniques and are thus able to couple relatively easily to circuitry and other device components. It has already been shown that coupled NV centres and flux qubits 19,20 are ideal complimentary elements for such hybrid systems. As both these device elements rely on spin they can easily be coupled, and experimental investigations have demonstrated quantum information transfer between flux qubit and NV centre ensembles 19 . Additionally, NV centres present ideal quantum logic elements and have shown to be useful for a range of operations including as quantum registers and as quantum gates 21,22 . Due to their possibility of realizing fault tolerant logic operations holonomic quantum gates have been widely studied in various systems 21-27 but most notably wit...

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“…Notice that recently a well known dynamically decoupling approach was applied for superconducting quantum computers to protect qubits from the environment [43].…”

Section: Simulation Of the Imperfections Of Quantum Memorymentioning

confidence: 99%

Quantum communication protocols as a benchmark for programmable quantum computers

Жуков

Kiktenko

Elistratov

et al. 2018

Quantum Inf Process

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We point out that realization of quantum communication protocols in programmable quantum computers provides a deep benchmark for capabilities of real quantum hardware. Particularly, it is prospective to focus on measurements of entropy-based characteristics of the performance and to explore whether a "quantum regime" is preserved. We perform proof-of-principle implementations of superdense coding and quantum key distribution BB84 E. O. K. was supported by ). W. V. P. acknowledges a support from RFBR (project no. 15-02-02128). Yu. E. L. acknowledges a support from RFBR (project no. 17-02-01134) and the Program of Basic Research of HSE. arXiv:1812.00587v1 [quant-ph] 3 Dec 2018 2 A. A. Zhukov et al.using 5-and 16-qubit superconducting quantum processors of IBM Quantum Experience. We focus on the ability of these quantum machines to provide an efficient transfer of information between distant parts of the processors by placing Alice and Bob at different qubits of the devices. We also examine the ability of quantum devices to serve as quantum memory and to store entangled states used in quantum communication. Another issue we address is an error mitigation. Although it is at odds with benchmarking, this problem is nevertheless of importance in a general context of quantum computation with noisy quantum devices. We perform such a mitigation and noticeably improve some results.Keywords quantum computer, quantum communication protocol, quantum algorithms, superdense coding, quantum benchmark IntroductionQuantum technologies based on manipulation with individual quantum objects and their quantum states are of great interest in problems of information transfer and processing. Historically, one of the first applications of quantum information technologies was quantum communication, and particularly, quantum key distribution (QKD) [1]. This technology utilizes features of quantum light in order to provide information-theoretic (unconditional) security for classical data transmission and storage [2,3]. Nowadays, there is a significant progress in experiments for providing long-distance point-to-point QKD links [4,5,6], as well as establishing multi-site quantum networks [7,8,9,10]. There are also other important developing areas of quantum communication such as secure direct communication [11,12,13], based on use of superdense coding [14], and transfering quantum states with quantum teleportation [15,16].Another field, which is undergoing dramatic progress, is quantum computation with different physical platforms, among which superconducting quantum circuits as well as trapped ions seem to be most prospective, see, e.g., Refs. [17,18]. Various quantum algorithms have been implemented to show concepts of error correction [19,20,21,22,23], modeling spectra of molecules [24] and other fermionic systems [25], simulation of light-matter systems [26], spin systems [27], many-body localization [28], machine learning [29], scaling issues [30] etc. However, in order to realize algorithms which are of practical importance, the quantum...

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Demonstration of Fidelity Improvement Using Dynamical Decoupling with Superconducting Qubits

Cited by 174 publications

References 55 publications

Detector tomography on IBM quantum computers and mitigation of an imperfect measurement

Detector tomography on IBM quantum computers and mitigation of an imperfect measurement

Experimental simulation of hybrid quantum systems and entanglement on a quantum computer

Quantum communication protocols as a benchmark for programmable quantum computers

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