Relaxation and Dephasing in a Two-Electron<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="bold">C</mml:mi><mml:mprescripts /><mml:none /><mml:mn>13</mml:mn></mml:mmultiscripts></mml:math>Nanotube Double Quantum Dot

Churchill, Hugh; Kuemmeth, Ferdinand; Harlow, Jennifer; Bestwick, Andrew; Rashba, Emmanuel I.; Flensberg, Karsten; Stwertka, C.; Taychatanapat, Thiti; Watson, Susan K.; Marcus, C. M.

doi:10.1103/physrevlett.102.166802

Cited by 140 publications

(259 citation statements)

References 32 publications

(54 reference statements)

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“…Nevertheless, spin blockade has been observed previously in carbon nanotubes [10,11,13]. In the spin blockade regime, transitions between a (1,1) and (0,2) charge state directly depend on whether the (1,1) state is a singlet or triplet.…”

mentioning

confidence: 93%

“…Our measurements thus present a first quantitative analysis of the complex admittance of a double quantum dot. The demonstrated technique also provides the basis for a simple and fast detection scheme for charge and spin state readout in carbon nanotubes -a material with considerable potential for spin-based quantum information processing [8][9][10][11][12][13] -without the need for a separate charge detector [14].…”

mentioning

confidence: 99%

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Measuring the Complex Admittance of a Carbon Nanotube Double Quantum Dot

Chorley¹,

Wabnig²,

Penfold-Fitch³

et al. 2012

Phys. Rev. Lett.

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We investigate radio-frequency (rf) reflectometry in a tunable carbon nanotube double quantum dot coupled to a resonant circuit. By measuring the in-phase and quadrature components of the reflected rf signal, we are able to determine the complex admittance of the double quantum dot as a function of the energies of the single-electron states. The measurements are found to be in good agreement with a theoretical model of the device in the incoherent limit. Besides being of fundamental interest, our results present an important step forward towards non-invasive charge and spin state readout in carbon nanotube quantum dots. PACS numbers: 73.63.Fg, 73.63.Kv, 73.23.Hk, 03.67.Lx An important requirement in any quantum information processing scheme is fast manipulation and readout of the quantum system in which the quantum information is encoded. This requires an understanding of the response of the quantum system at finite frequencies which, in the case of an electronic device, involves an understanding of its complex admittance [1,2]. Of particular interest in the context of quantum information processing are double quantum dots which are widely used to define charge and spin qubits [3]. However, while double quantum dots have been investigated in detail over the last decade, experiments to measure and analyze their complex admittance have not yet been performed and this topic has only recently been addressed theoretically [4]. The admittance of quantum dots at finite frequencies is non-trivial as exemplified by recent experiments on single quantum dots [5,6]. The physics is even richer for double quantum dots as internal charge dynamics, i.e. charge transfer between the quantum dots, has to be taken into account. However, the dependence of the admittance on the internal charge dynamics also provides a route towards charge and spin state readout [7].In this work we present a detailed experimental study of the complex admittance of a carbon nanotube double quantum dot which is measured using rf reflectometry techniques. The measurements are compared with a theoretical model of the device where we use a density matrix approach to calculate the double quantum dot admittance. The good quantitative agreement between the experimental and theoretical results allows us to determine the effective conductance and susceptance of the double dot as a function of the energies of the single-electron states. Our measurements thus present a first quantitative analysis of the complex admittance of a double quantum dot. The demonstrated technique also provides the basis for a simple and fast detection scheme for charge and spin state readout in carbon nanotubes -a material with considerable potential for spin-based quantum information processing [8-13] -without the need for a separate charge detector [14].The device we consider is a carbon nanotube grown by chemical vapour deposition on degenerately doped Si ter- minated by 300 nm SiO 2 , see Fig. 1(a). The nanotube is contacted by Au source and drain electrodes which form the outer ...

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mentioning

confidence: 93%

mentioning

confidence: 99%

Measuring the Complex Admittance of a Carbon Nanotube Double Quantum Dot

Chorley¹,

Wabnig²,

Penfold-Fitch³

et al. 2012

Phys. Rev. Lett.

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“…18,20 In general, the coupling of the electron spin to its orbital motion is a relativistic effect for electrons moving in external electric fields. Asymmetric confinements in semiconductor QDs ͑extrinsic SO coupling, see Ref.…”

Section: ͑1͒mentioning

confidence: 99%

“…15 Recent experiments have shown that it is indeed possible to confine electrons in single [16][17][18][19] and double QDs ͑DQDs͒ in a CNT by means of electrostatic gates in cleanly grown small band-gap nanotubes. 5,15,20 The present study is motivated by these experimental results.…”

Section: Introductionmentioning

confidence: 99%

“…Even though this is a weak coupling compared to heavier atoms, the combined effect of curvature and intra-atomic SO coupling splits a fourfolddegenerate level into two Kramers doublets by a fraction of a millielectron volt. The demonstration of electrostatically confined particles in CNT-QDs in the presence of SO coupling 18,20 has motivated recent theoretical investigations. The single-electron QD setup and, in particular, the influence of the electron-phonon coupling on the decoherence are subjects of a work by Bulaev et al 34 The two-particle problem has been studied numerically in Refs.…”

Section: Introductionmentioning

confidence: 99%

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Spin-orbit effects in carbon-nanotube double quantum dots

Weiss¹,

Rashba²,

Kuemmeth³

et al. 2010

Phys. Rev. B

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We study the energy spectrum of symmetric double quantum dots in narrow-gap carbon nanotubes with one and two electrostatically confined electrons in the presence of spin-orbit and Coulomb interactions. Compared to GaAs quantum dots, the spectrum exhibits a much richer structure because of the spin-orbit interaction that couples the electron's isospin to its real spin through two independent coupling constants. In a single dot, both constants combine to split the spectrum into two Kramers doublets while the antisymmetric constant solely controls the difference in the tunneling rates of the Kramers doublets between the dots. For the two-electron regime, the detailed structure of the spin-orbit split energy spectrum is investigated as a function of detuning between the quantum dots in a 22-dimensional Hilbert space within the framework of a single-longitudinalmode model. We find a competing effect of the tunneling and Coulomb interaction. The former favors a left-right symmetric two-particle ground state while in the regime where the Coulomb interaction dominates over tunneling, a left-right antisymmetric ground state is found. As a result, ground states on both sides of the ͑11͒-͑02͒ degeneracy point may possess opposite left-right symmetry, and the electron dynamics when tuning the system from one side of the ͑11͒-͑02͒ degeneracy point to the other is controlled by three selection rules ͑in spin, isospin, and left-right symmetry͒. We discuss implications for the spin-dephasing and Pauli blockade experiments.

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Nanomaterials for Quantum Information Science and Engineering

et al. 2022

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Quantum information science and engineering (QISE) which entails generation, control and manipulation of individual quantum mechanical states together with nanotechnology have dominated condensed matter physics and materials science research in the 21st century. Solid state devices for QISE have, to this point, predominantly been designed with bulk material as their constituents. In this review, we consider how nanomaterials or low-dimensional materials i.e. materials with intrinsic quantum confinement -may offer inherent advantages over conventional materials for QISE. We identify the materials challenges for specific types of qubits, and we identify how emerging nanomaterials may overcome these challenges. Challenges for and progress towards nanomaterials-based quantum devices are identified. We aim to help close the gap between the nanotechnology and quantum information communities and inspire research that will lead to next-generation quantum devices for scalable and practical quantum applications.

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Relaxation and Dephasing in a Two-ElectronC13Nanotube Double Quantum Dot

Cited by 140 publications

References 32 publications

Measuring the Complex Admittance of a Carbon Nanotube Double Quantum Dot

Measuring the Complex Admittance of a Carbon Nanotube Double Quantum Dot

Spin-orbit effects in carbon-nanotube double quantum dots

Nanomaterials for Quantum Information Science and Engineering

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