Real Time Electron Tunneling and Pulse Spectroscopy in Carbon Nanotube Quantum Dots

Götz, G.; Steele, Gary A.; Vos, Willem-Jan; Kouwenhoven, Leo P.

doi:10.1021/nl802892q

Cited by 20 publications

(21 citation statements)

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“…The holy grail here could be the realization of a coherent coupling between spin and motion. Another inspiration from the field of qubits is the use of nanotubes as on-chip charge sensors (Biercuk et al, 2006;Gotz et al, 2008;, or as a component in circuit quantum electrodynamics (Delbecq et al, 2011). If long coherence times could be achieved, there is potential for a dramatically improved charge sensor (Dial et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Early single-electron transistors were contacted in this way (Bockrath et al, 1997), as were the first double quantum dots . Although cleanliness and fabrication-induced disorder are a concern, devices fabricated this way have demonstrated ambipolar operation and discrete excited states (Biercuk et al, 2005), as well as charge sensing and pulsed gate spectroscopy (Biercuk et al, 2006;Gotz et al, 2008).…”

Section: Top Gatingmentioning

confidence: 99%

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Quantum transport in carbon nanotubes

et al. 2015

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Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike in conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and valley freedom. The interplay between the two is the focus of this review. The energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are explained, together with their consequences for transport measurements through nanotube quantum dots. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli blockade. This can be exploited to read out spin and valley qubits and to measure the decay of these states through coupling to nuclear spins and phonons. A second unique property of carbon nanotubes is that the combination of valley freedom and electron-electron interactions in one dimension strongly modifies their transport behavior. Interaction between electrons inside and outside a quantum dot is manifested in SU(4) Kondo behavior and level renormalization. Interaction within a dot leads to Wigner molecules and more complex correlated states. This review takes an experimental perspective informed by recent advances in theory. As well as the well-understood overall picture, open questions for the field are also clearly stated. These advances position nanotubes as a leading system for the study of spin and valley physics in one dimension where electronic disorder and hyperfine interaction can both be reduced to a low level.

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Section: Discussionmentioning

confidence: 99%

Section: Top Gatingmentioning

confidence: 99%

Quantum transport in carbon nanotubes

et al. 2015

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“…Most parameters of the proposed setup can be tuned. The frequency ω depends on the length of the nanotube section that is suspended, while the frequency difference ∆, the tunneling rates T c , Γ L , and Γ R , can be controlled by the external gates [40]. However, little is known on electron dephasing in nanotubes: the rate Γ d remains to be measured and it is not clear whether Γ d can be tailored so to fulfill Γ d < ω.…”

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confidence: 99%

Cooling Carbon Nanotubes to the Phononic Ground State with a Constant Electron Current

2009

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We present a quantum theory of cooling of a mechanical resonator using back-action with constant electron current. The resonator device is based on a doubly clamped nanotube, which mechanically vibrates and acts as a double quantum dot for electron transport. Mechanical vibrations and electrons are coupled electrostatically using an external gate. The fundamental eigenmode is cooled by absorbing phonons when electrons tunnel through the double quantum dot. We identify the regimes in which ground state cooling can be achieved for realistic experimental parameters.Cooling mechanical resonators has recently attracted considerable interest, as it allows ultrasensitive detection of mass [1,2,3,4], of mechanical displacements [5], and of spin [6]. An appealing prospect is to cool the mechanical resonator to its phononic ground state. This achievement would open the possibility to create and manipulate non classical states at the macroscopic scale and to study the transition from the classical to the quantum regime [7,8,9].The lowest phononic occupation number achieved so far has been experimentally realized by cooling down the resonator in a dilution fridge [10]. Another promising approach is to employ back-action, which consists of coupling mechanical oscillations to visible or microwave photons [11,12,13,14,15,16,17,18,19]. Recently, it has been theoretically proposed [20,21,22] and experimentally demonstrated [10] that back-action cooling can be achieved by coupling mechanical resonators to the constant electron current through electronic nano-devices, such as normal-metal and superconducting single-electron transistors. This approach is appealing because it is easy to implement in a dilution fridge as compared to techniques based on photons. Within this approach, however, modest occupations of the phononic ground state have been predicted [19,20,21,22]. In particular, using an analogy with laser cooling of atoms [23], back-action cooling by constant electron current in these systems is essentially analogous to Doppler cooling [21].In this Letter, we theoretically demonstrate ground state cooling of a mechanical nanotube resonator using constant electron current. Specifically, the nanotube is employed both as the mechanical resonator and the electronic device through which the current flows. In addition, we consider the device layout in which the nanotube acts as a double quantum dot (DQD). This setup allows us to access an analogous regime of sideband cooling of the oscillator [23]. Calculations are carried out by including the coupling of the resonator to the thermal noise of the electrodes and the effect of electronic dephasing inside the DQD. For realistic device parameters the temperature is lowered by a factor of about 100. Moreover, we identify the regime in which the oscillator ground state can reach more than 90% occupation.The device layout is sketched in Fig. 1(a). The DQD system is obtained by locally depleting a semiconducting nanotube with gate T [24,25,26,27]. The dot on the right is suspended, so it...

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“…The measurement of individual electrons or its spins in GaAs quantum dots (QDs) has been realized by so-called charge detection via a nearby quantum point contact (QPC) or single electron transistor (SET) (Lu et al, 2003;Elzerman et al, 2004a). In particular, the combination of high speed and high charge sensitivity has made SET useful in studying a wide range of physical phenomena such as discrete electron transport (Lu et al, 2003;Bylander et al, 2005;Gotz et al, 2008), qubit read out (Lehnert et al, 2003;Duty et al, 2004;Vijay et al, 2009) and nanomechanical oscillators (Knobel et al, 2003;Lahaye et al, 2004). So far, most SETs have been using Al/AlO x /Altunnel junctions.…”

Section: A Graphene Quantum Dot With a Single Electron Transistor As mentioning

confidence: 99%