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~ 6-10 months

~12 months

SAW-driven single-electron current

Light emission from

SAW-driven electron-hole recombination

  • GaAs/AlGaAs undoped heterostructure

  • Planar n-p junction

Optimisation:

  • n-p junction design
  • p-region design
  • RF electronics
  • ZnO layer deposition
  • OPTICS: New cryogenic optical scanning microscope

(300mK)

  • CAPE: optimisation of optic fibre

MBE, EBL, Deposition techniques, SEM, AFM, fast-timing electronics, RF electrical techniques.

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6

~ 28-24 months

Plan of Action

Quantum Technologies

Flying qubits

&

a polarised single-photon source

SAW-driven single-photon emission

Thank you.

"Universal computation"

encryption

computing

communications

Flying Electron qubits and a polarised single-photon source

- Impact & Motivation -

- Flying electron qubits and a polarised single photon -source

- Plan & Timeline -

- Six-stage plan details-

Carmen Palacios Berraquero

Supervisors:

Prof Chris Ford

Prof Richard Phillips

Prof Richard Penty

  • Single photons :

high repetition rate

low probability of overlap.

  • Optical detection - collaboration with Prof. Phillips (AMOP)
  • Microscope optimisation
  • Fast detectors and timing electronics
  • Increasing directionality & detection efficiency

  • Prove single-photons
  • correlation measurements

Initialise Manipulate Entangle Read-out

NanoDTC PhD Proposal 2014 - 2017

25th June 2014

Barnes et al. Phys. Rev. B 62.12 (2000): 8410.

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4

5

~ 2nd half of third year

~ first half of 3rd year

Spin injection

through ferromagnetic contacts

Spin initialisation:

through external magnetic field

  • Deposition and study in collaboration with Thin FIlms and Magnetism (TFM)

Saw-driven polarised light!

Spin manipulation

using nanomagnets

Polarisation: electron's spin maps onto a combination of left and right-circularly polarised states

Polarisation changes through optic fibre (CAPE)

Build a well-defined polarised source inside microscope

Build polarisation controller: 1/4 and 1/2 wavelength waveplates to separate R and L

Optics collaboration

(McNeil et al., Nano Lett., 10, 1549 (2010)

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9

Relevance for the Nano Centre

Previous Work

Uses of single-photon sources

Undoped GaAs/AlGaAs heterostructure

Quantum Transport Dynamics & Electrical Engineering & High-precision Optics

Advantages of proposed device

Device Optimisation:

1D channel design

Device Optimisation:

Collaboration with CAPE

Other single-photon sources

  • SP group created the field by proposing SAW-driven pumps:

Shilton et al., J. Phys.: Condens. Matt., 8, L531 (1995).

  • Demonstrated SAW taking single-electron back and forth between QDs 4microns

McNeil et al., Nature, 477, 439 (2011)

  • SAW-driven light demonstrated for first time in 2008 (LH figure)

Gell et al., App. Phys. Lett. 93, 081115 (2008)

  • Excitation schemes
  • Atoms, ions in gas phase
  • Organic molecules
  • Colour centres
  • Semiconductor nanocrystals
  • Self-assembled quantum dots
  • Once again in Pisa in 2009 (RH figure)

De Simoni et al., App. Phys. Lett. 94, 121103 (2009)

  • Decreasing potential barrier

  • Hole region:

increase hole density

decrease size of recombination region

  • Measurement of weak absorptions

  • Random number generation: key ingredients for information processing
  • computational methods
  • cryptography (for the generation of encrypting keys)

  • Quantum information processing: photons would present specific advantages :
  • Photons are in principle identical and indistinguishable, and they are weakly coupled to the environment.
  • photons can transport the information from processor to processor
  • If computation can be performed on photons, they can serve as "flying qubits"

Low-dimensional systems & confinement

Spintronics

Piezoelectricity

Fabrication & Characterisation techniques

Material depositions

fast-timing electronics

low-temp dynamics

low-noise measurements (300mK)

AFM

SEM

XRD

EBL

MBE

  • No need for single-spin readout:
  • ensemble of identical electrons

  • Reduction of random errors through:
  • averaging over an ensemble reduces spin fluctuations
  • using undoped material
  • no need for pico-second switching of gates
  • The flying-qubit scheme: electrons less sensitive to fluctuations

  • Long-distance communications:
  • enabled by the flying-qubit scheme
  • Nanomagnets have been demonstrated before within the group

McNeil et al., Nano Lett., 10, 1549 (2010)

1. Deposition of ZnO layer

sputtering

XRD

2. RF electronics

improving RF holder

improving isolation

noise-detection / signal isolation techniques

Main Method: computational modeling (group code / COMSOL)

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September '14

6 months

SAW-driven single-electron current

Creating a single-photon source

Light emission from SAW-driven electron-hole recombination

12 months

18 months

SAW-driven single-photon emission

24 months

SAW-driven polarised light emission from magnetic field

Spin manipulation

30 months

Spin-injection from ferromagnetic contact into SAW minimum

September '17

Spin manipulation using nanomagnets

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