The terahertz region (1-10 THz) has potential applications in many areas, such as chemical sensing, medical imaging and free-space optical communications. With the demonstration of terahertz sources, it is quite necessary to develop the detection technology in terahertz. Here we propose an electrically tunable quantum dot infrared photodetector to detect the terahertz region. The proposed detec...

We use the spin-polarized excitons in a single quantum dot to design optical controls for basic operations in quantum computing. We examine the ultrafast nonlinear optical processes required and use the coherent nonlinear optical responses to deduce if such processes are physically reasonable. The importance and construction of an entangled state of polarized exciton states in a single quantum ...

In a two-dimensional quantum dot in a GaAs heterostructure, the spin-orbit scattering rate is substantially reduced below the rate in a bulk two-dimensional electron gas @B. I. Halperin et al., Phys. Rev. Lett. 86, 2106 ~2001!#. Such a reduction can be undone if the spin-orbit coupling parameters acquire a spatial dependence, which can be achieved, e.g., by a metal gate covering only a part of ...

We have studied the electron transport through a quantum dot coupled to three leads in the presence of external microwave fields supplied to different parts of the considered mesoscopic system. Additionally, we introduced a possible nonresonant tunneling channels between leads. The quantum dot charge and currents were determined in terms of the appropriate evolution operator matrix elements and...

The stability of dynamic dipole-dipole interactions in a quantum dot array is estimated, and a novel solid state quantum CCN (controlled controlled not) gate having a block structure of quantum dot array is proposed. Quantum mechanical coherence is expected to be maintained, and both the bit error and the phase error are reduced by the ensemble effects in the block. The overall process of quant...

We propose a scheme for implementing quantum gates and entanglement between spin qubits in the outer dots of a triple-dot system with an empty central dot. The voltage applied to the central dot can be tuned to realize the gate. Our scheme exemplifies the possibility of quantum gates outside the regime where each dot has an electron, so that spin-spin exchange interaction is not the only releva...

We show that individual colloidal CdSe-core quantum dots can be optically trapped and manipulated in three dimensions by an infrared continuous wave laser operated at low laser powers. This makes possible utilizing quantum dots not only for visualization but also for manipulation, an important advantage for single molecule experiments. Moreover, we provide quantitative information about the mag...

We report on correlated real-time detection of individual electrons in an InAs nanowire double quantum dot. Two self-aligned quantum point contacts in an underlying two-dimensional electron gas material serve as highly sensitive charge detectors for the double quantum dot. Tunnel processes of individual electrons and all tunnel rates are determined by simultaneous measurements of the correlated...

Fluorescence resonance energy transfer in complexes of semiconductor CdSe/ZnS quantum dots with molecules of heterocyclic azo dyes, 1-(2-pyridylazo)-2-naphthol and 4-(2-pyridylazo) resorcinol, formed at high quantum dot concentration in the polymer pore track membranes were studied by steady-state and transient PL spectroscopy. The effect of interaction between the complexes and free quantum do...

We report on the effects of patterning and layering on multilayer InAs/GaAs(001) quantum dot structures laterally ordered using an in vacuo focused ion beam. The patterned hole size and lateral pattern spacing affected the quantum dot size and the fidelity of the quantum dots with respect to the lateral patterns. 100% pattern fidelity was retained after six layers of dots for a 9.0 ms focused i...