Experimental and theoretical challenges for the trapped electron quantum computer

Marzoli, Irene; Tombesi, Paolo; Ciaramicoli, G.; Werth, G.; Bushev, Pavel; Ståhl, S.; Schmidt‐Kaler, F.; Hellwig, M.; Henkel, Carsten; Marx, G.; Jex, Igor; Stachowska, E.; Szawiola, G.; Walaszyk, A.

doi:10.1088/0953-4075/42/15/154010

Cited by 29 publications

(31 citation statements)

References 67 publications

(109 reference statements)

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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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Section: Practical Considerations For Coupling An Electron To a Smentioning

confidence: 99%

Hybrid quantum systems with trapped charged particles

2017

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“…[13] concludes that it is not because the anharmonicity will always be too great, and it also reports that a thermal width narrower than 5 kHz could not be calculated for any N -gap trap where N is anything between 1 and 6. The only hope offered was that a much smaller trap might make the damping rate large enough to observe one electron despite the anharmonicity inherent in planar traps [13,14]. Indeed, Eq.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…These observations made possible the most precise measurements of the electron magnetic moment and the fine structure constant [2]. The one-electron observations also triggered intriguing studies on using oneelectron qubits as building blocks for quantum information processing [3][4][5][6][7][8][9][10][11][12][13][14]. The possibility of a very long coherence time is very attractive.…”

Section: Introductionmentioning

confidence: 99%

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Optimized planar Penning traps for quantum information studies

Goldman¹,

Gabrielse²

2011

TCP 2010

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A one-electron qubit would offer a new option for quantum information science, including the possibility of extremely long coherence times. One-quantum cyclotron transitions and spin flips have been observed for a single electron in a cylindrical Penning trap. However, an electron suspended in a planar Penning trap is a more promising building block for the array of coupled qubits needed for quantum information studies. The optimized design configurations identified here promise to make it possible to realize the elusive goal of one trapped electron in a planar Penning trap for the first time -a substantial step toward a one-electron qubit.

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“…The challenging goal of using single electrons in Penning traps for quantum information [1][2][3][4][5][6] has motivated intense research towards a completely new generation of devices. The so-called planar Penning traps [7] are specifically designed to meet the demands of quantum computation, thus allowing for scalability as well as improved addressability of the trapped particles.…”

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confidence: 99%

From a single- to a double-well Penning trap

2010

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The new generation of planar Penning traps promises to be a flexible and versatile tool for quantum information studies. Here, we propose a fully controllable and reversible way to change the typical trapping harmonic potential into a double-well potential, in the axial direction. In this configuration a trapped particle can perform coherent oscillations between the two wells. The tunneling rate, which depends on the barrier height and width, can be adjusted at will by varying the potential difference applied to the trap electrodes. Most notably, tunneling rates in the range of kHz are achievable even with a trap size of the order of 100 µm.The challenging goal of using single electrons in Penning traps for quantum information [1-6] has motivated intense research towards a completely new generation of devices. The so-called planar Penning traps [7] are specifically designed to meet the demands of quantum computation, thus allowing for scalability as well as improved addressability of the trapped particles. Moreover, new pixel microstructures promise to generate complex electric potentials, suitable both for particle transport and trapping in racetrack and artificial crystal configurations [8]. The first planar Penning traps were operated in Mainz [9, 10] and in Ulm [11] both at room temperature and in a cryogenic environment. However, the elusive goal of a single trapped electron has not yet been achieved. The major obstacle is the anharmonicity in the axial potential, which prevents the detection of a single electron. To overcome this difficulty new theoretical studies [12] have carefully analyzed the geometry of planar Penning traps, with the aim of optimizing the harmonicity of the axial potential. The results are extremely encouraging and may lead to the first experimental demonstration of a single electron in a planar Penning trap.Here we demonstrate the versatility of a planar Penning trap. In fact, it is able to produce a smooth variation of the trapping axial potential from a standard harmonic well into a double well. This result is achieved by applying suitable static voltages to the trap electrodes. The experimenter can control both the barrier height and width, simply by adjusting the potential difference between the electrodes. In particular, we have simulated the behavior of an optimized mirror-image planar Penning trap, which consists of two identical sets of electrodes facing each other. An electron, initially trapped in a singlewell harmonic potential, can be adiabatically placed in a double-well potential. Depending on the energy of the axial motion, the particle wave function may spread over for several microns, through the barrier between the two wells. Therefore, the particle motional state could be prepared in a superposition of left and right, with the particle being, at the same time, in both wells. Hence, if a single electron trapped in a Penning trap forms a socalled geonium atom [13], the electron in the double-well potential can mimic a giant molecule along the lines of Ref. [14]. More...

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Experimental and theoretical challenges for the trapped electron quantum computer

Cited by 29 publications

References 67 publications

Hybrid quantum systems with trapped charged particles

Hybrid quantum systems with trapped charged particles

Optimized planar Penning traps for quantum information studies

From a single- to a double-well Penning trap

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