Coherent Coupling of Two Dopants in a Silicon Nanowire Probed by Landau-Zener-Stückelberg Interferometry

Dupont-Ferrier, Eva; Roche, B.; Voisin, B.; Jehl, X.; Wacquez, R.; Vinet, M.; Sanquer, M.; Franceschi, S. De

doi:10.1103/physrevlett.110.136802

Cited by 81 publications

(107 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The accumulated phase between these repeated tunneling events gives place to constructive or destructive interferences, depending on the driving amplitude and the detuning from the avoided crossing. These LZS interferences have been observed in a variety of quantum systems, such as Rydberg atoms, 2 superconducting qubits, [3][4][5][6][7][8][9][10][11][12][13][14][15] ultracold molecular gases, 16 quantum dot devices, [17][18][19][20][21][22][23][24][25] single spins in nitrogen vacancy centers in diamond, 26,27 nanomechanical circuits, 28 and ultracold atoms in accelerated optical lattices. 29 Several other related experimental and theoretical works have studied LZS interferometry in systems under different shapes of periodic driving, [30][31][32][33][34][35] in two coupled qubits, 36 in optomechanical systems, 37 and the effect of a geometric phase.…”

Section: Introductionmentioning

confidence: 99%

Dynamic transition in Landau-Zener-Stückelberg interferometry of dissipative systems: The case of the flux qubit

2016

View full text Add to dashboard Cite

We study Landau-Zener-Stuckelberg (LZS) interferometry in multilevel systems coupled to an Ohmic quantum bath. We consider the case of superconducting flux qubits driven by a dc+ac magnetic fields, but our results can apply to other similar systems. We find a dynamic transition manifested by a symmetry change in the structure of the LZS interference pattern, plotted as a function of ac amplitude and dc detuning. The dynamic transition is from a LZS pattern with nearly symmetric multiphoton resonances to antisymmetric multiphoton resonances at long times (above the relaxation time). We also show that the presence of a resonant mode in the quantum bath can impede the dynamic transition when the resonant frequency is of the order of the qubit gap. Our results are obtained by a numerical calculation of the finite time and the asymptotic stationary population of the qubit states, using the Floquet-Markov approach to solve a realistic model of the flux qubit considering up to 10 energy levels.

show abstract

Section: Introductionmentioning

confidence: 99%

Dynamic transition in Landau-Zener-Stückelberg interferometry of dissipative systems: The case of the flux qubit

2016

View full text Add to dashboard Cite

show abstract

“…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.…”

mentioning

confidence: 99%

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

et al. 2014

View full text Add to dashboard Cite

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...

show abstract

“…Experiments on individual TLS provide important quantum properties 5,[22][23][24] , but have previously been restricted to an alumina tunneling barrier and must characterize many TLS, one at a time, in order to extract an average dipole moment of the film. The Landau-Zener effect has been used to study a wide variety of qubit systems, including superconducting circuits [25][26][27] , silicon-dopants 28 , and quantum dots 29 . A recent theory using this effect predicts that TLS can be characterized using the quantum dynamics created by two simultaneous fields 30 .…”

mentioning

confidence: 99%

Landau-Zener population control and dipole measurement of a two-level-system bath

et al. 2014

View full text Add to dashboard Cite

Tunneling two level systems (TLS), present in dielectrics at low temperatures, have been recently studied for fundamental understanding and superconducting device development. According to a recent theory by Burin et al., the TLS bath of any amorphous dielectric experiences a distribution of Landau-Zener transitions if exposed to simultaneous fields. In this experiment we measure amorphous insulating films at millikelvin temperatures with a microwave field and a swept electric field bias using a superconducting resonator. We find that the maximum dielectric loss per microwave photon with the simultaneous fields is approximately the same as that in the equilibrium state, in agreement with the generic material theory. In addition, we find that the loss depends on the fields in a way which allows for the separate extraction of the TLS bath dipole moment and density of states. This method allows for the study of the TLS dipole moment in a diverse set of disordered films, and provides a technique for continuously inverting their population.In quantum computing, two-level systems (TLS) in dielectrics have been found to function as an environmental bath for superconducting quantum elements 1-4 and as quantum memory bits in a hybrid quantum computer 5 . The environmental impact of the deleterious bath has led to improved materials 6-8 for superconducting qubits. In recent qubit designs 9,10 the geometrical architecture allows only for a small amount of electrical energy storage in the deleterious amorphous metal oxides. Over four decades ago, a now standard model of TLS was introduced which describes charged nanoscale systems moving independently in a distribution of double well potentials, presumably created by undercoordinated bonds 11,12 . Recent measurements of individual TLSs under application of a strain field are in agreement with this model 13 . Although the TLS effects are generally known, the precise identity of the atomic defects or bonds that comprise the TLS and dipole moments from a given material are generally not known [14][15][16] . Furthermore, it was found that the sudden application of strain or electric fields can result in an immediate change in the TLS density, followed by a slow glassy relaxation to the equilibrium state 17-19 , possibly caused by weak TLS-TLS interactions 20,21 .In the case of resonant microwave measurements, the loss tangent is proportional to the weighted TLS densitythe TLS density times the dipole moment squared. Experiments on individual TLS provide important quantum properties 5,22-24 , but have previously been restricted to an alumina tunneling barrier and must characterize many TLS, one at a time, in order to extract an average dipole moment of the film. The Landau-Zener effect has been used to study a wide variety of qubit systems, including superconducting circuits 25-27 , silicon-dopants 28 , and quantum dots 29 . A recent theory using this effect predicts that TLS can be characterized using the quantum dynamics created by two simultaneous fields 30 . Experimental real...

show abstract

Coherent Coupling of Two Dopants in a Silicon Nanowire Probed by Landau-Zener-Stückelberg Interferometry

Cited by 81 publications

References 29 publications

Dynamic transition in Landau-Zener-Stückelberg interferometry of dissipative systems: The case of the flux qubit

Dynamic transition in Landau-Zener-Stückelberg interferometry of dissipative systems: The case of the flux qubit

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

Landau-Zener population control and dipole measurement of a two-level-system bath

Contact Info

Product

Resources

About