~ 6-10 months
~12 months
SAW-driven single-electron current
Light emission from
SAW-driven electron-hole recombination
- GaAs/AlGaAs undoped heterostructure
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.
~ 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
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.
~ 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)
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
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)