Coherent Adiabatic Spin Control in the Presence of Charge Noise Using Tailored Pulses

Ribeiro, Hugo; Burkard, Guido; Petta, J. R.; Lü, Hong; Gossard, A. C.

doi:10.1103/physrevlett.110.086804

Cited by 46 publications

(50 citation statements)

References 31 publications

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“…1(b). Although the dynamics of the system under "double hat" pulses has already been studied experimentally 18 , there is still a need to gain a better understanding of the charge-noise-induced spin dephasing. We will show, among other things, that the measurement of finite-time LZSM oscillations can provide a tool to qualitatively access the strength of charge noise.…”

Section: Adiabatic Control Of a S − T+ Qubitmentioning

confidence: 99%

“…Recently, it has been proposed to use a two-spin basis consisting of the singlet S and triplet T + spin states [16][17][18] . Quantum control of the S-T + qubit relies on LandauZener-Stückelberg-Majorana [19][20][21][22] (LZSM) physics, which occurs in the system when the S-T + qubit is repeatedly swept through the hyperfine mediated S-T + anticrossing.…”

Section: Introductionmentioning

confidence: 99%

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Interplay of charge and spin coherence in Landau-Zener-Stückelberg-Majorana interferometry

2013

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We study Landau-Zener dynamics in a double quantum dot filled with two electrons, where the spin states can become correlated with charge states, and the level velocity can be tuned in a timedependent fashion. We show that a correct interpretation of experimental data is only possible when finite-time effects are taking into account. In addition, our formalism allows the study of partial adiabatic dynamics in the presence of phonon-mediated hyperfine relaxation and charge noise induced dephasing. Our findings demonstrate that charge noise severely impacts the visibility of LZSM interference fringes. This indicates that charge coherence must be treated on an equal footing with spin coherence.

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Section: Adiabatic Control Of a S − T+ Qubitmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Interplay of charge and spin coherence in Landau-Zener-Stückelberg-Majorana interferometry

2013

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“…The probability to remain in the initial qubit state, P LZ = exp(−π∆ 2 /2 v), thereby grows with the velocity v = d /dt, here assumed to be constant [1][2][3][4]. Because the relative phase between the split wavepackets depends on their energy evolutions, repeated passages by a periodic modulation (t) =¯ +A cos(Ωt), give rise to so-called LZSM quantum interference [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. We present a breakthrough which * These authors contributed equally to this work.…”

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confidence: 99%

Characterization of Qubit Dephasing by Landau-Zener-Stückelberg-Majorana Interferometry

et al. 2014

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Controlling coherent interaction at avoided crossings is at the heart of quantum information processing. The regime between sudden switches and adiabatic transitions is characterized by quantum superpositions that enable interference experiments. Here, we implement periodic passages at intermediate speed in a GaAs-based two-electron charge qubit and observe Landau-Zener-Stückelberg-Majorana (LZSM) quantum interference of the resulting superposition state. We demonstrate that LZSM interferometry is a viable and very general tool to not only study qubit properties but beyond to decipher decoherence caused by complex environmental influences. Our scheme is based on straightforward steady state experiments. The coherence time of our two-electron charge qubit is limited by electron-phonon interaction. It is much longer than previously reported for similar structures.LZSM interferometry is a double-slit kind experiment which, in principle, can be realized with any qubit, while the specific measurement protocol might vary. Our system is a charge qubit based on two-electron states in a lateral double quantum dot (DQD) embedded in a twodimensional electron system (2DES) (Fig. 1). Source and drain leads at chemical potentials µ S,D , each tunnel coupled to one dot, allow current flow by single-electron tunneling. Applying the voltage V = (µ S − µ D )/e = 1 mV across the DQD (Fig. 1B) we use this current to detect the steady-state properties of the driven system. We interprete the singlets, S 11 (one electron in each dot) and S 20 (two electrons in the left dot), as qubit states. They form an avoided crossing (Fig. 1C), described by the Hamiltonianwhere we consider a variable energy detuning (t) and a constant inter-dot tunnel coupling tuned to ∆ 13 µeV, corresponding to a clock speed of ∆/h 3.1 GHz, where h is the Planck constant. Let us first discuss a single sweep through the avoided crossing at = 0: as shown back in 1932 independently by Landau, Zener, Stckelberg, and Majorana it brings the qubit into a superposition state [1][2][3][4], the electronic analog to the optical beam splitter. The probability to remain in the initial qubit state, P LZ = exp(−π∆ 2 /2 v), thereby grows with the velocity v = d /dt, here assumed to be constant [1][2][3][4]. Because the relative phase between the split wavepackets depends on their energy evolutions, repeated passages by a periodic modulation (t) =¯ +A cos(Ωt), give rise to so-called LZSM quantum interference [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. We present a breakthrough which * These authors contributed equally to this work.makes LZSM interferometry a powerful tool: it is based on systematic measurements together with a realistic model, which explicitly includes the noisy environment. We demonstrate how to decipher the detailed qubit dynamics and directly determine its decoherence time T 2 based on straightforward steady state measurements. Keeping the experiment simple we detect the dccurrent I through the DQD. It involves electron tunneling giving rise to the confi...

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“…The cases of unequally coupled and/or sized dots, and different shapes of the bias [21] are in general treatable by our numerics and will be the subject of our future studies. Charge noise [42][43][44] is neglected in the current model. Investigating the significance of charge coherence requires an extension of the numerical tools we use [43], and is planned as a forthcoming investigation.…”

Section: Conclusion and Final Remarksmentioning

confidence: 99%

“…Charge noise [42][43][44] is neglected in the current model. Investigating the significance of charge coherence requires an extension of the numerical tools we use [43], and is planned as a forthcoming investigation.…”

Section: Conclusion and Final Remarksmentioning

confidence: 99%

Interplay of spin-orbit and hyperfine interactions in dynamical nuclear polarization in semiconductor quantum dots

Rančić

Burkard

2014

Phys. Rev. B

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We theoretically study the interplay of spin-orbit and hyperfine interactions in dynamical nuclear polarization in two-electron semiconductor double quantum dots near the singlet (S) -triplet (T+) anticrossing. The goal of the scheme under study is to extend the singlet (S) -triplet (T0) qubit decoherence time T * 2 by dynamically transferring the polarization from the electron spins to the nuclear spins. This polarization transfer is achieved by cycling the electron spins over the S − T+ anticrossing. Here, we investigate, both quantitatively and qualitatively, how this hyperfine mediated dynamical polarization transfer is influenced by the Rashba and Dresselhaus spin-orbit interaction. In addition to T * 2 , we determine the singlet return probability Ps, a quantity that can be measured in experiments. Our results suggest that the spin-orbit interaction establishes a mechanism that can polarize the nuclear spins in the opposite direction compared to hyperfine mediated nuclear spin polarization. In materials with relatively strong spin-orbit coupling, this interplay of spin-orbit and hyperfine mediated nuclear spin polarizations prevents any notable increase of the S − T0 qubit decoherence time T * 2 .

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Coherent Adiabatic Spin Control in the Presence of Charge Noise Using Tailored Pulses

Cited by 46 publications

References 31 publications

Interplay of charge and spin coherence in Landau-Zener-Stückelberg-Majorana interferometry

Interplay of charge and spin coherence in Landau-Zener-Stückelberg-Majorana interferometry

Characterization of Qubit Dephasing by Landau-Zener-Stückelberg-Majorana Interferometry

Interplay of spin-orbit and hyperfine interactions in dynamical nuclear polarization in semiconductor quantum dots

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