Multiplexing of radio-frequency single-electron transistors

Stevenson, Thomas; Pellerano, F.; Stahle, C. M.; Aidala, Katherine; Schoelkopf, Robert

doi:10.1063/1.1472472

Cited by 39 publications

(27 citation statements)

References 11 publications

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“…In this paper, we experimentally demonstrate coherent spin manipulation in a three-spin qubit defined in a triple quantum dot. Initialization, spin manipulation, and measurement of the qubit state using multiplexed reflectometry 9,10 are demonstrated. The gate noise is estimated based on decoherence rates.…”

Section: Introductionmentioning

confidence: 99%

Coherent spin manipulation in an exchange-only qubit

Laird¹,

Taylor²,

DiVincenzo³

et al. 2010

Phys. Rev. B

237

304

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Initialization, manipulation, and measurement of a three-spin qubit are demonstrated using a few-electron triple quantum dot, where all operations can be driven by tuning the nearest-neighbor exchange interaction. Multiplexed reflectometry, applied to two nearby charge sensors, allows for qubit readout. Decoherence is found to be consistent with predictions based on gate voltage noise with a uniform power spectrum. The theory of the exchange-only qubit is developed and it is shown that initialization of only two spins suffices for operation. Requirements for full multi-qubit control using only exchange and electrostatic interactions are outlined.Comment: related work at http://marcuslab.harvard.ed

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Section: Introductionmentioning

confidence: 99%

Coherent spin manipulation in an exchange-only qubit

Laird¹,

Taylor²,

DiVincenzo³

et al. 2010

Phys. Rev. B

237

304

View full text Add to dashboard Cite

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“…[14]. The rf-QPC may also be useful in detecting small changes in mesoscopic capacitance [28] that alter its resonance frequency and in the simultaneous measurement of many rf-QPCs using multiplexing techniques [29,30].…”

mentioning

confidence: 99%

Fast single-charge sensing with a rf quantum point contact

Reilly

Marcus

Hanson

et al. 2007

Applied Physics Letters

267

292

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We report high-bandwidth charge sensing measurements using a GaAs quantum point contact embedded in a radio frequency impedance matching circuit (rf-QPC). With the rf-QPC biased near pinch-off where it is most sensitive to charge, we demonstrate a conductance sensitivity of 5 × 10−6 e 2 /h Hz −1/2 with a bandwidth of 8 MHz. Single-shot readout of a proximal few-electron double quantum dot is investigated in a mode where the rf-QPC back-action is rapidly switched.Mesoscopic charge sensors such as the single-electron transistor (SET) [1] and the quantum point contact (QPC) [2] are at the heart of many readout technologies for quantum information processing. As electrometers, their intrinsic sensitivity [3,4] provides efficient measurement with detector noise close to the minimum allowed by quantum mechanics [5]. When combined with highbandwidth operation, these devices are attractive for application in metrology [6,7], single photon detection [8], and as non-invasive charge probes at the nanoscale [9,10,11].Combining sensitivity with fast operation is challenging because of the large RC time of the detector resistance (> 50 kΩ) and shunt capacitance of wire between the cold stage of a cryostat and room-temperature electronics (hundreds of pF). Nevertheless several demonstrations of single-electron detection have been reported with bandwidths in the tens of kHz [12,13,14]. An approach [15] that circumvents the difficulty of wiring capacitance uses an impedance matching network on resonance to transform the high resistance of the detector towards the Z 0 = 50 Ω characteristic impedance of a transmission line. Changes in device resistance modulate the reflected or transmitted [16] power of a radio frequency (rf) carrier, tuned to the resonance frequency. Application of this reflectometry technique to aluminum based SETs has demonstrated charge sensing [9], near quantum-limited sensitivity [4,17], and bandwidths above 100 MHz [15].In this Letter, we extend rf reflectometry to a semiconductor quantum point contact. We describe the reflectometer circuit in detail and explore its performance as a fast, cryogenic charge sensor, demonstrating singleelectron sensing with 8 MHz bandwidth. In the regime of operation, intrinsic shot noise of the QPC makes up approximately 80% of the total system noise. Previous work [18,19] has demonstrated modulation of rf power by a point contact operated as a voltage-controlled resistor. Here, we demonstrate application of the QPC as a fast charge sensor by performing charge-state readout of an integrated double quantum dot [20] with fixed total charge. In addition, we present single-shot measurements of the double dot in a mode where the rf-QPC carrier is rapidly switched, modulating the measurement back-action on a time-scale of 50 ns.The device, shown in Fig. 1(a), consists of a GaAs/Al 0.3 Ga 0.7 As heterostructure with two dimensional electron gas (density 2 × 10 15 m −2 , mobility 20 m 2 /Vs) 100 nm below the surface. Ti/Au top gates define a few-electron double dot with proximal QPC....

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“…Low-pass filtered output voltages from each mixer are proportional to the change in respective device resistance. The use of frequency-domain multiplexing al- lows both the SET and nanotube to be monitored using a common transmission line and cryogenic amplifier [18,19]. Bias-tees on the circuit board enable standard dc transport measurements of both devices.…”

mentioning

confidence: 99%

Charge sensing in carbon-nanotube quantum dots on microsecond timescales

et al. 2006

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We report fast, simultaneous charge sensing and transport measurements of gate-defined carbon nanotube quantum dots. Aluminum radio frequency single electron transistors (rf-SETs) capacitively coupled to the nanotube dot provide single-electron charge sensing on microsecond timescales. Simultaneously, rf reflectometry allows fast measurement of transport through the nanotube dot. Charge stability diagrams for the nanotube dot in the Coulomb blockade regime show extended Coulomb diamonds into the high-bias regime, as well as even-odd filling effects, revealed in charge sensing data.Carbon nanotubes are promising systems on which to base coherent electronic devices [1][2][3]. Due to a combination of strong confinement, quantized phonon spectrum [4], and zero nuclear spin, carbon nanotubes are likely to exhibit long-lived coherent states. Key to the success of this technology is the ability to manipulate electron states within a nanotube and perform fast, efficient readout. Recent advances in device fabrication [3,[5][6][7][8] allow the creation of multiple quantum dots along the length of a tube with controllable coupling by applying voltage biases to electrostatic top-gates. However, readout of these structures has been limited to dc transport, which is invasive and slow compared to relevant coherence times [9].In this Letter, we describe the integration of superconducting aluminum radio frequency single electron transistors (rf-SETs) [10] with carbon nanotube quantum dot devices defined by electrostatic gates [8]. The rf-SET serves as a sensitive electrometer [11] and, when capacitively coupled to the nanotube dot, provides a means of non-invasively detecting its charge state on short timescales and in regimes not accessible with transport measurements [12][13][14][15][16]. These represent the first charge sensing experiments with nanotube quantum dots using integrated charge detection. In addition, we make use of radio-frequency (rf) reflectometry that enables fast transport measurements of the nanotube correlated with fast charge sensing by the capacitively coupled rf-SET. Previous work [17] has used reflectometry to investigate the microwave impedance of nanotubes and transistor action at low (Hz) frequencies. The present study advances previous work by simultaneously carrying out charge sensing together with rf transport as well as by gaining five orders of magnitude in time resolution.Carbon nanotubes were grown from patterned Fe catalyst islands on a Si/SiO 2 wafer via chemical vapor deposition. Single-walled tubes with diameters less than ∼ 4nm were identified using atomic force microscopy and selectively contacted via electron beam lithography [3]. Contacts made from ∼ 15 nm of Pd [6] were connected to larger metallic pads defined by optical lithography. The entire device was then coated with ∼ 35nm Al 2 O 3 using low-temperature atomic layer deposition (ALD). Three top-gates were then aligned to each nanotube: two "barrier gates" (B1, B2) to deplete the underlying nanotube, defining a quantum dot, with ...

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Multiplexing of radio-frequency single-electron transistors

Cited by 39 publications

References 11 publications

Coherent spin manipulation in an exchange-only qubit

Coherent spin manipulation in an exchange-only qubit

Fast single-charge sensing with a rf quantum point contact

Charge sensing in carbon-nanotube quantum dots on microsecond timescales

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