Trapped electron coupled to superconducting devices

Bushev, Pavel; Bothner, Daniel; Nagel, J.; Kemmler, M.; Konovalenko, K. B.; Lőrincz, András; Ilin, K.; Siegel, M.; Koelle, D.; Kleiner, R.; Schmidt‐Kaler, F.

doi:10.1140/epjd/e2011-10517-6

Cited by 19 publications

(17 citation statements)

References 47 publications

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“…Our very preliminary studies of high-field operation of YBCO GBJ SQUIDs with 2 μm wide junctions demonstrate that such devices can operate in large in-plane fields of 1 T [36]. The presented solution for calculating the spin sensitivity for arbitrary SQUID geometries-as a function of position and orientation of the magnetization of small spin particlesprovides an important tool for the systematic optimization of the spin sensitivity using nanoSQUIDs as sensitive devices for direct detection of magnetization switching of small spin particles.…”

Section: Discussionmentioning

confidence: 85%

Resistively shunted YBa₂Cu₃O₇grain boundary junctions and low-noise SQUIDs patterned by a focused ion beam down to 80 nm linewidth

Nagel

Konovalenko

Kemmler

et al. 2010

Supercond. Sci. Technol.

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YBa 2 Cu 3 O 7 24 • (30 •) bicrystal grain boundary junctions (GBJs), shunted with 60 nm (20 nm) thick Au, were fabricated by focused ion beam milling with widths 80 nm w 7.8 μm. At 4.2 K we find critical current densities j c in the 10 5 A cm −2 range (without a clear dependence on w) and an increase in resistance times junction area ρ n with an approximate scaling ρ n ∝ w 1/2. For the narrowest GBJs j c ρ n = I c R n ≈ 100 μV (with critical current I c and junction resistance R n), which is promising for the realization of sensitive nanoSQUIDs for the detection of small spin systems. We demonstrate that our fabrication process allows the realization of sensitive nanoscale dc SQUIDs; for a SQUID with w ≈ 100 nm wide GBJs we find an rms magnetic flux noise spectral density of S 1/2 ≈ 4 μ 0 Hz −1/2 in the white noise limit. We also derive an expression for the spin sensitivity S 1/2 μ , which depends on S 1/2 , on the location and orientation of the magnetic moment of a magnetic particle to be detected by the SQUID, and on the SQUID geometry. For the unoptimized SQUIDs presented here, we estimate S 1/2 μ = 390 μ B Hz −1/2 , which could be further improved by at least an order of magnitude.

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Section: Discussionmentioning

confidence: 85%

Resistively shunted YBa₂Cu₃O₇grain boundary junctions and low-noise SQUIDs patterned by a focused ion beam down to 80 nm linewidth

Nagel

Konovalenko

Kemmler

et al. 2010

Supercond. Sci. Technol.

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“…An optimization of the design of the planar trap electrodes [73] led to the detection of one or two electrons [74]. The outlook for planar Penning traps is discussed elsewhere [74][75][76].…”

Section: Practical Considerations For Coupling An Electron To a Smentioning

confidence: 99%

Hybrid quantum systems with trapped charged particles

2017

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Trapped charged particles have been at the forefront of quantum information processing (QIP) for a few decades now, with deterministic two-qubit logic gates reaching record fidelities of 99.9% and single qubit operations of much higher fidelity. In a hybrid system involving trapped charges, quantum degrees of freedom of macroscopic objects such as bulk acoustic resonators, superconducting circuits or nano-mechanical membranes, couple to the trapped charges and ideally inherit the coherent properties of the charges. The hybrid system therefore implements a "quantum transducer", where the quantum reality (i.e. superpositions and entanglement) of small objects is extended to include the larger object. Although a hybrid quantum system with trapped charges could be valuable both for fundamental research and for QIP application, no such system exists today. Here we study theoretically the possibilities of coupling the quantum mechanical motion of a trapped charged particle (e.g. ion or electron) to quantum degrees of freedom of superconducting devices, nano-mechanical resonators and quartz bulk acoustic wave resonators. For each case, we estimate the coupling rate between the charged particle and its macroscopic counterpart and compare it to the decoherence rate, i.e. the rate at which quantum superposition decays. A hybrid system can only be considered quantum if the coupling rate significantly exceeds all decoherence rates. Our approach is to examine specific examples, using parameters that are experimentally attainable in the foreseeable future. We conclude that those hybrid quantum system considered involving an atomic ion are unfavorable, compared to using an electron, since the coupling rates between the charged particle and its counterpart are slower than the expected decoherence rates. A system based on trapped electrons, on the other hand, might have coupling rates which significantly exceed decoherence rates. Moreover it might have appealing properties such as fast entangling gates, long coherence and flexible electron interconnectivity topology. Realizing such a system, however, is technologically challenging, since it requires accommodating both trapping technology and superconducting circuitry in a compatible manner. We review some of the challenges involved, such as the required trap parameters, electron sources, electrical circuitry and cooling schemes in order to promote further investigations towards the realization of such a hybrid system. CONTENTS

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“…We discuss strategies to further improve the nanoSQUID performance. Recent developments in miniaturized submicron-sized direct current (dc) superconducting quantum interference devices (SQUIDs) are motivated by the need of sensitive detectors for small spin systems such as molecular magnets 1-3 and magnetic nanoparticles, 4 cold atom clouds 5 or single electrons and atoms 6 and improved resolution in scanning SQUID microscopy. [7][8][9][10][11][12] As a common approach, nanoSQUIDs based on constriction Josephson junctions (JJs) have been used, [13][14][15][16][17] achieving root mean square (rms) flux noise power S 1/2 Φ down to a few 100 nΦ 0 /Hz 1/2 (Φ 0 is the magnetic flux quantum) in magnetically shielded environment.…”

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confidence: 99%

Nb nano superconducting quantum interference devices with high spin sensitivity for operation in magnetic fields up to 0.5 T

Wölbing

Nagel

Schwarz

et al. 2013

Applied Physics Letters

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We investigate electric transport and noise properties of microstrip-type submicron direct current superconducting quantum interference devices (dc SQUIDs) based on Nb thin films and overdamped Josephson junctions with a HfTi barrier. The SQUIDs were designed for optimal spin sensitivity S 1/2 µ upon operation in intermediate magnetic fields B (tens of mT), applied perpendicular to the substrate plane. Our so far best SQUID can be continuously operated in fields up to B ≈ ±50 mT with rms flux noise S 1/2 Φ,w ≤ 250 nΦ0/Hz 1/2 in the white noise regime and spin sensitivity S 1/2 µ ≤ 29 µB/Hz 1/2 . Furthermore, we demonstrate operation in B = 0.5 T with high sensitivity in flux S 1/2 Φ,w ≈ 680 nΦ0/Hz 1/2 and in electron spin S 1/2 µ ≈ 79 µB/Hz 1/2 . We discuss strategies to further improve the nanoSQUID performance.

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Trapped electron coupled to superconducting devices

Cited by 19 publications

References 47 publications

Resistively shunted YBa₂Cu₃O₇grain boundary junctions and low-noise SQUIDs patterned by a focused ion beam down to 80 nm linewidth

Resistively shunted YBa₂Cu₃O₇grain boundary junctions and low-noise SQUIDs patterned by a focused ion beam down to 80 nm linewidth

Hybrid quantum systems with trapped charged particles

Nb nano superconducting quantum interference devices with high spin sensitivity for operation in magnetic fields up to 0.5 T

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Trapped electron coupled to superconducting devices

Cited by 19 publications

References 47 publications

Resistively shunted YBa2Cu3O7grain boundary junctions and low-noise SQUIDs patterned by a focused ion beam down to 80 nm linewidth

Resistively shunted YBa2Cu3O7grain boundary junctions and low-noise SQUIDs patterned by a focused ion beam down to 80 nm linewidth

Hybrid quantum systems with trapped charged particles

Nb nano superconducting quantum interference devices with high spin sensitivity for operation in magnetic fields up to 0.5 T

Contact Info

Product

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Resistively shunted YBa₂Cu₃O₇grain boundary junctions and low-noise SQUIDs patterned by a focused ion beam down to 80 nm linewidth

Resistively shunted YBa₂Cu₃O₇grain boundary junctions and low-noise SQUIDs patterned by a focused ion beam down to 80 nm linewidth