Photon- and phonon-assisted tunneling in the three-dimensional charge stability diagram of a triple quantum dot array

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

doi:10.1063/1.4798335

Cited by 20 publications

(18 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Further, the switching persists when reducing the sensor bias to 5 μV, far below the Δ ∼ 150 μeV of the short diamond axis. This rules out sensor backaction, which is observed at larger biases and exhibits a pronounced bias dependence [36][37][38][39][40][41], unlike the metastability seen here. Thus, this suggests an intrinsic DD process rather than an extrinsic effect as the origin for the switching.…”

mentioning

confidence: 96%

Intrinsic Metastabilities in the Charge Configuration of a Double Quantum Dot

et al. 2015

View full text Add to dashboard Cite

We report a thermally activated metastability in a GaAs double quantum dot exhibiting real-time charge switching in diamond shaped regions of the charge stability diagram. Accidental charge traps and sensor backaction are excluded as the origin of the switching. We present an extension of the canonical double dot theory based on an intrinsic, thermal electron exchange process through the reservoirs, giving excellent agreement with the experiment. The electron spin is randomized by the exchange process, thus facilitating fast, gate-controlled spin initialization. At the same time, this process sets an intrinsic upper limit to the spin relaxation time. DOI: 10.1103/PhysRevLett.115.106804 PACS numbers: 73.21.La, 73.23.Hk, 73.63.Kv Spins in quantum dots [1] are promising candidates for the realization of qubits-the elementary units of a quantum computer. Great progress was made in recent years towards implementing quantum information processing schemes with electron spins in GaAs quantum dots [2][3][4][5][6][7][8], which hold the potential for scaling to a large number of qubits [9][10][11]. Stable qubits with long coherence times are of crucial importance to execute numerous coherent quantum gates. Spin echo and dynamical decoupling techniques were successfully employed to isolate the electronic system from the slowly fluctuating nuclear spins of the GaAs host material [3,[12][13][14][15], enhancing the coherence time T 2 from below 1 μs to much longer times exceeding 0.2 ms. A fundamental limit T 2 ≤ 2T 1 is set by the spin relaxation time T 1 . In a magnetic field, spins relax through spin-phonon coupling mediated by the spin-orbit interaction [2,[16][17][18]. Since here the spin-orbit coupling is weak, very long T 1 times result, exceeding 1 s at 1 T [19], leaving ample room for further improvements of the spin qubit coherence.In this Letter, we report the experimental observation of a thermal electron exchange process via the reservoirs of a quantum dot, setting an intrinsic upper bound to T 1 , which can be orders of magnitude lower than the fundamental spin-phonon limit [16]. The resulting metastable charge states-appearing in the double dot (DD) in the absence of interdot tunneling-make the exchange process detectable with a charge sensor. Within a diamond shaped region, the DD switches its charge state back and forth over time from an electron on the left dot to an electron on the right dot without direct interdot tunneling. After excluding unintentional charge traps and sensor backaction, we present an extension of the orthodox DD transport theory accounting very well for the observations. The exchange process can be used for fast qubit initialization [7]. Finally, we outline ways to extend T 1 up to the spin-phonon limit.The sample is fabricated from a GaAs heterostructure with a 2D electron gas 110 nm below the surface (density 2.6 × 10 11 cm −2 and mobility 4 × 10 5 cm 2 =V s). The device layout, see Fig. 1(a), is adopted from Ref. [20]. Each dot adjacent to the DD (center) acts as a charge sensor [...

show abstract

mentioning

confidence: 96%

Intrinsic Metastabilities in the Charge Configuration of a Double Quantum Dot

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Photon assisted transport in nanostructures has been object of intense research 2 . We mention only those references close to this work in double barriers [5][6][7][8][9] and quantum dots 4,[10][11][12][13][14][15][16][17][18][19][20][21] . An additional and important effect of photon assisted tunneling is the renormalization of the tunnel couplings which become dependent on the parameters of the driving.…”

Section: Introductionmentioning

confidence: 99%

Photon assisted long-range tunneling

Gallego-Marcos

Sánchez

Platero

2015

Journal of Applied Physics

View full text Add to dashboard Cite

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.

show abstract

“…The phonon-assisted tunnelling effect is regarded as an important source of tunnelling, so that a thorough study is needed to understand its effects. So far, it has been observed both in semiconductor QDs [11] and in lateral QD molecules [12]. The origin of PhAT is the Coulomb interaction between an excitation of a QD molecule and the surrounding lattice, and occurs when the excitation transfer implies an energy mismatch, which is compensated by the emission or absorption of a phonon, so that an important portion of PhAT described by the phonon spectral density [13].…”

Section: Introductionmentioning

confidence: 99%

Phonon-assisted tunnelling in a double quantum dot molecule immersed in a cavity

Vargas-Calderón

Vinck-Posada

2019

Optik

View full text Add to dashboard Cite

The effects caused by phonon-assisted tunnelling (PhAT) in a double quantum dot (QD) molecule immersed in a cavity were studied under the quantum Markovian master equation formalism in order to account for dissipation phenomena.We explain how for higher PhAT rates, a stronger interaction between a QD and the cavity at off-resonance takes place through the resonant interaction of another QD and the cavity, where the QDs interact through tunnelling. A closer look at the system's allowed optical transitions as a function of PhAT rates showed coalescence of the transition energies, leading to a loss of spectroscopic resolution in the photoluminescence (PL) spectrum. This coalescence occurs at several exceptional points, suggesting a quantum dynamical phase transition.

show abstract

Photon- and phonon-assisted tunneling in the three-dimensional charge stability diagram of a triple quantum dot array

Cited by 20 publications

References 16 publications

Intrinsic Metastabilities in the Charge Configuration of a Double Quantum Dot

Intrinsic Metastabilities in the Charge Configuration of a Double Quantum Dot

Photon assisted long-range tunneling

Phonon-assisted tunnelling in a double quantum dot molecule immersed in a cavity

Contact Info

Product

Resources

About