In optical materials energy is usually extracted only from the lowest excited state, resulting in fundamental energy-efficiency limits such as the Shockley-Queisser limit for single-junction solar cells. Photon-cutting materials provide a way around such limits by absorbing high-energy photons and 'cutting' them into multiple low-energy excitations that can subsequently be extracted. The occurr...

We compare three different types of optical qubits for information transfer via quantum teleportation and direction transmission under photon losses. The three types of qubits are (1) qubits using the vacuum and the single-photon (VSP) states, (2) single-photon qubits using polarization degrees of freedom, i.e., polarized single-photon (PSP) qubits, and (3) coherent-state qubits that use two co...

Because of the ultrafast and photon-driven nature transport in their active region, we demonstrate that quantum cascade lasers can be operated as resonantly amplified terahertz detectors with wide RF bandwidth. Tunable responsivities up to 50 V/W noise equivalent powers down 100 pW/Hz1/2 are demonstrated at 4.7 THz. Constant peak respect detector temperature observed 80 K. Thanks ?ps intersub-b...

Engineering light at the single photon level is a long-standing goal in physics. In this thesis, we investigate optical nonlinearities at the single photon level orchestrated by an optical cavity. We demonstrate an all-optical transistor where one stored ‘gate’ photon controls the propagation of a ’source’ light beam. The system is based on EIT and a highcooperativity cavity. Each ’gate’ photon...

Non-degenerate 2-photon excitation (ND-2PE) of a fluorophore with two laser beams of different photon energies offers an independent degree of freedom in tuning of the photon flux for each beam. This feature takes advantage of the infrared wavelengths used in degenerate 3-photon excitation (D-3PE) microscopy to achieve increased penetration depths, while preserving a relatively high 2-photon ex...

All optical detectors to date annihilate photons upon detection, thus excluding repeated measurements. Here, we demonstrate a robust photon detection scheme that does not rely on absorption. Instead, an incoming photon is reflected from an optical resonator containing a single atom prepared in a superposition of two states. The reflection toggles the superposition phase, which is then measured ...

Broadband light sources play essential roles in diverse fields, such as high-capacity optical communications, optical coherence tomography, optical spectroscopy, and spectrograph calibration. Although a nonclassical state from spontaneous parametric down-conversion may serve as a quantum counterpart, its detection and characterization have been a challenging task. Here we demonstrate the direct...

iv PENELOPE-2008: A CODE SYSTEM FOR MONTE CARLO SIMULATION OF ELECTRON AND PHOTON TRANSPORT – © OECD/NEA 2008 Abstract The computer code system PENELOPE (version 2008) performs Monte Carlo simulation of coupled electron-photon transport in arbitrary materials for a wide energy range, from a few hundred eV to about 1 GeV. Photon transport is simulated by means of the standard, detailed simulatio...

A lead bis(ethynyl)porphyrin polymer possesses strong nonlinear absorption with unprecedented spectral/temporal coverage as a result of broad, overlapping two-photon and excited-state absorption bands with favorable excited-state dynamics. Consequently, this material exhibits effective optical limiting over a range of about 500 nm in the near infrared (ca. 1050 – 1600 nm) and for laser pulsewid...