Long-distance coherent coupling in a quantum dot array

Braakman, Floris; Barthelemy, Pierre; Reichl, Christian; Wegscheider, Werner; Vandersypen, L. M. K.

doi:10.1038/nnano.2013.67

Cited by 139 publications

(152 citation statements)

References 34 publications

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“…Such a longrange charge transfer is relevant for chemical reactions 23 and has analogues in quantum optics 22 . The recent advances in the tunability of triple quantum dots [24][25][26][27][28][29][30] has remarkably achieved the observation of this effect [31][32][33] . It entails the transfer of charge or spin between the two ends of the triple dot via superpositions that do not include the center one 34 , opening the way to the transfer of quantum information between distant qubits with low decoherence.…”

Section: Introductionmentioning

confidence: 98%

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Photon assisted long-range tunneling

Gallego-Marcos

Sánchez

Platero

2015

Journal of Applied Physics

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We analyze long-range transport through an ac driven triple quantum dot with one single electron. An effective model is proposed for the analysis of photoassisted cotunnel in order to account for the virtual processes which dominate the long-range transport, which takes place at n-photon resonances between the edge quantum dots. The AC field renormalizes the inter dot hopping, modifying the levels hybridization. It results in a non trivial behavior of the current with the frequency and intensity of the external ac field.

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Section: Introductionmentioning

confidence: 98%

“…Stückelberg interference patterns arise for the multiphotonic long-range excitations 32 . As triple dots constitute a tunable three level system, they are ideal platforms to investigate multilevel quantum interference 21,43 .…”

Section: Introductionmentioning

confidence: 99%

Photon assisted long-range tunneling

Gallego-Marcos

Sánchez

Platero

2015

Journal of Applied Physics

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“…Recently, long-range coupling of electrons located in the two outer quantum dots of a linear triple dot system has been demonstrated [35,36]. The effective exchange interaction in that system arises from electron cotunneling between the outer dots and exhibits the fourth-order dependence on tunneling amplitudes that is characteristic of superexchange [37], but suffers from a large virtual energy cost from the doubly occupied center dot states.…”

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confidence: 99%

Tunable Spin-Qubit Coupling Mediated by a Multielectron Quantum Dot

Srinivasa

Taylor

2015

Phys. Rev. Lett.

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We present an approach for entangling electron spin qubits localized on spatially separated impurity atoms or quantum dots via a multi-electron, two-level quantum dot. The effective exchange interaction mediated by the dot can be understood as the simplest manifestation of RudermanKittel-Kasuya-Yosida exchange, and can be manipulated through gate voltage control of level splittings and tunneling amplitudes within the system. This provides both a high degree of tuneability and a means for realizing high-fidelity two-qubit gates between spatially separated spins, yielding an experimentally accessible method of coupling donor electron spins in silicon via a hybrid impurity-dot system.Single spins in solid-state systems represent versatile candidates for scalable quantum bits (qubits) in quantum information processing architectures [1][2][3][4][5][6]. In many proposals involving single-spin qubits localized on impurity atoms [2,7] and within quantum dots [1,8], two-qubit coupling schemes harness the advantages of tunnelingbased nearest-neighbor exchange interactions: exchange gates are rapid, tunable, and protected against multiple types of noise [9][10][11][12][13]. These features have been demonstrated for electron spins in quantum dots [14][15][16][17], while a similar demonstration for spins localized on impurity atoms such as phosphorus donors in silicon remains an outstanding experimental challenge [6]. Although the exchange interaction originates from the longrange Coulomb interaction, its strength typically decays exponentially with distance [8,18]. Long-range coupling via concatenation of multiple nearest-neighbor interactions is not ideal for coupling spatially separated electron spins, as it sets a low threshold error rate below which fault-tolerant quantum computing is feasible [19,20]. A mechanism for long-range coupling that simultaneously enables scalability and robustness against errors is therefore key to realizing practical spin-based quantum information processing devices.Approaches to implementing long-range interactions typically involve identifying a system that acts as a mediator of the interaction between the qubits, with proposed systems including optical cavities and microwave stripline resonators [21][22][23][24][25][26] [32,33], and multi-electron molecular cores [34]. Recently, long-range coupling of electrons located in the two outer quantum dots of a linear triple dot system has been demonstrated [35,36]. The effective exchange interaction in that system arises from electron cotunneling between the outer dots and exhibits the fourth-order dependence on tunneling amplitudes that is characteristic of superexchange [37], but suffers from a large virtual energy cost from the doubly occupied center dot states. In contrast, a many-electron quantum dot in the center can also couple distant spins via the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, with low-energy intermediate states [38], but perhaps at the cost of low fidelity as impurityFermi sea correlations become hard to disentangle...

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“…Further experiments that can be envisioned with this architecture are e.g. electron charge and electron spin buses, measurements of long distance coherent coupling [20], and single spin CCD [21]. …”

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confidence: 99%

Reconfigurable quadruple quantum dots in a silicon nanowire transistor

Betz

Tagliaferri

Vinet

et al. 2016

Applied Physics Letters

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We present a novel reconfigurable metal-oxide-semiconductor multi-gate transistor that can host a quadruple quantum dot in silicon. The device consist of an industrial quadruple-gate silicon nanowire field-effect transistor. Exploiting the corner effect, we study the versatility of the structure in the single quantum dot and the serial double quantum dot regimes and extract the relevant capacitance parameters. We address the fabrication variability of the quadruple-gate approach which, paired with improved silicon fabrication techniques, makes the corner state quantum dot approach a promising candidate for a scalable quantum information architecture.Semiconductor quantum bits relying on the charge or spin degree of freedom of a single electron, bound to a quantum dot (QD) or impurity atom, are considered promising candidates for the base elements of solid state quantum computing architectures [1]. Building a successful quantum computer, however, requires a scalable multi-qubit approach to implement the necessary algorithms [2]. Electron spins bound to silicon QDs are seen as promising candidates for this due to their long coherence time, electrical tunability and flexible coupling geometries [3][4][5]. A further advantage of using Si is the possibility to integrate with current complementary-metaloxide-semiconductor (CMOS) technology [5-8] and leverage its established industrial platform for large scale circuits. Recently, the integration of Si quantum dots and double quantum dots (DQD) into CMOS technology has been taken a step further with reports of fewelectron QDs, DQDs, and donor-QD hybrids created within industry-standard Si nanowire transistors [9][10][11][12]. Combined with a gate-based readout scheme that alleviates the need for a separate charge sensor [10-14] these approaches pave the way towards a large scale quantum computing architecture based on current CMOS technology.In this Letter, we report on a reconfigurable QD and DQD system in a quadruple-gate CMOS transistor. It incorporates one, or a pair, of CMOS corner state quantum dots [10,11] in a variety of configurations. Each of the four gates can host an independently tunable quantum dot created in the square channel by electrostatic enhancement and confinement resulting from the topgate electrodes and accompanying silicon nitride spacers. We characterise one exemplary single QD and demonstrate that different DQD configurations can be set at will. Building on previous demonstrations [10][11][12] results provide a way to scale up CMOS quantum information architectures and to create reconfigurable silicon multi-dot arrangements. The device presented here is a fully depleted silicon-oninsulator (FDSOI) nanowire field-effect transistor with four independently addressable top-gates. The polyarXiv:1603.03636v1 [cond-mat.mes-hall]

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Long-distance coherent coupling in a quantum dot array

Cited by 139 publications

References 34 publications

Photon assisted long-range tunneling

Photon assisted long-range tunneling

Tunable Spin-Qubit Coupling Mediated by a Multielectron Quantum Dot

Reconfigurable quadruple quantum dots in a silicon nanowire transistor

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