IQST Grad School Project

Single electron pumped single photon source

PhD Students:

  • t.b.a. (Stuttgart)


  • Prof. P. Michler (Stuttgart)
  • Prof. J. Weis (MPI)
  • Prof. J. van Slageren (Stuttgart)

Project Description:

In this project we aim to realize an on-demand single-photon source pumped via a single- electron pump (SEP) based on the Coulomb blockade effect. To our knowledge, such a device has never been realized and would have a strong impact as a new metrological standard. The device is built up of a single-electron pump for regulation of the stream of single electrons and a single quantum dot which serves as a single-photon source. The electrons will tunnel into the QD which is fed with holes provided via a p-doped layer (fig. a). The radiative recombination triggered by the injection of a single electron will generate one single photon. The dot will be embedded into a semiconductor waveguide (fig. b and d) so that the emitted photons will be guided with a high coupling efficiency and finally coupled to a fiber for efficient photon collection. The resulting device will be at first a single-photon source triggered by single-carrier injection, so giving a more complex flavor to the definition of “on-demand” single-photon source. This kind of device will be of great interest as a new metrological standard as well as a photon source in high yield quantum information processing. The single-electron pump will be incorporated into the tip of a scanning probe microscope (see figure c), allowing precision placement of the single-electron pump with respect to the quantum dot. As a further development, a molecular “spin aligning” material with a stable magnetic moment at low (helium) temperatures will be added into the single-electron pump. This molecular material will spin polarize the electron injected into the QD which will result in photon emission with a well-defined polarization, feature of great interest for quantum information applications. Specifically, we will employ the [TbPc2] molecule, because of its large magnetic moment and because it can be sublimed intact. We will functionalize the molecule to stimulate growth of ordered arrays on surfaces. The use of a molecular material rather than a ferromagnet such as cobalt or permalloy minimizes the invasive effect of metallic electrodes on the single photon source. The molecular (mono)layer may also function as the final electron island of the electron pump.