Single photon emission and detection at the nanoscale utilizing semiconductor nanowires

We report recent progress toward on-chip single photon emission and detection in the near infrared utilizing semiconductor nanowires. Our single photon emitter is based on a single InAsP quantum dot embedded in a p-n junction defined along the growth axis of an InP nanowire. Under forward bias, light is emitted from the single quantum dot by...

Quantum dots on bilayer graphene made on a substrate of boron nitride using split gates

In this project a method has been developed to fabricate the device structure for a quantum dot on bilayer graphene made on a boron nitride substrate. Quantum dots in bilayer graphene give us the ability to study the special properties of electrons inside this material; including a gapless electron-hole crossover and a fourfold degeneracy of...

Quantum Dots and Andreev Reflections in Graphene

Graphene is an exceptionally thin semiconductor that consists of only one atomic layer of carbon atoms. The electrons in graphene live in a strictly two-dimensional (2D) world. In addition to this remarkable 2Dness, it is also peculiar that the behavior of the electrons in graphene is governed by the Dirac equation rather than the well known...

Single electron-ics with carbon nanotubes

We experimentally investigate Quantum Dots, formed in Carbon Nanotubes. The first part of this thesis deals with charge sensing on such quantum dots. The charge sensor is a metallic Single-electron-transistor, sensitive to the charge of a single electron on the quantum dot. We use this technique for real-time charge readout and precise tuning of...

Quantum optics with single nanowire quantum dots

In this paper we present our recent developments in control and manipulation of individual spins and photons in a single nanowire quantum dot. Specific examples include demonstration of optical excitation of single spin states, charge tunable quantum devices and single photon sources. We will also discuss our recent discovery of a new type of...

Electrical manipulation and detection of single electron spins in quantum dots

Entanglement in Solid-State Nanostructures

The goal of this thesis is to investigate theoretically the generation and behaviour of multipartite entanglement for solid-state nanosystems, in particular electron spin quantum bits (so-called 'qubits') in quantum dots. A quantum dot is a tiny potential well where a single electron can be trapped. A quantum bit can be implemented in this...

Josephson squelch filter for quantum nanocircuits

We fabricated and tested a squelch circuit consisting of a copper powder filter with an embedded Josephson junction connected to ground. For small signals (squelch ON), the small junction inductance attenuates strongly from dc to at least 1 GHz, while for higher frequencies dissipation in the copper powder increases the attenuation exponentially...

Potential of semiconductor nanowires for single photon sources

The catalyst-assisted growth of semiconductor nanowires heterostructures offers a very flexible way to design and fabricate single photon emitters. The nanowires can be positioned by organizing the catalyst prior to growth. Single quantum dots can be formed in the core of single nanowires which can then be easily isolated and addressed to...

Cryogenic amplifier for fast real-time detection of single-electron tunneling

The authors employ a cryogenic high electron mobility transistor (HEMT) amplifier to increase the bandwidth of a charge detection setup with a quantum point contact (QPC) charge sensor. The HEMT is operating at 1?K and the circuit has a bandwidth of 1?MHz. The noise contribution of the HEMT at high frequencies is only a few times higher than...

Analytical solution of the time evolution of an entangled electron spin pair in a double quantum dot nanostructure

Using master equations, we present an analytical solution of the time evolution of an entangled electron spin pair which can occupy 36 different quantum states in a double quantum dot nanostructure. This solution is exact, given a few realistic assumptions, and takes into account relaxation and decoherence rates of the electron spins as...

Connection between noise and quantum correlations in a double quantum dot

We investigate the current and noise characteristics of a double quantum dot system. The strong correlations induced by the Coulomb interaction and the Pauli principle create entangled two-electron states and lead to signatures in the transport properties. We show that the interaction parameter Ø, which measures the admixture of the double...