Infrared Spectroscopy with Visible Light

Abstract

Spectral measurements in the infrared (IR) optical range provide unique fingerprints of materials which are useful for material analysis, environmental sensing, and health diagnostics 1 Entangled photons continue to play a crucial role in advancing many areas of quantum technologies, including cryptography 4,5 , computing 6,7 and metrology 8,9 . They can be obtained using a variety of methods, with SPDC in non-linear optical crystals, being well established 10 .We consider a specific type of interference technique, referred to as a non-linear interferometry, which is analogue to a conventional Mach-Zehnder or Young interferometer but with the two splitting mirrors being substituted with two SPDC crystals 3 . In a non-linear interferometer, two SPDC crystals are pumped by a common laser, so that down-converted photons (signal and idler) from one crystal are injected into the second crystal. Signal and idler photons from the two crystals interfere and produce a distinctive interference pattern in frequency and spatial domains. Depending on experimental configuration one can observe interference either in intensity or in the second-order correlation function [11][12][13] .One remarkable feature of non-linear interferometers is that the interference pattern for signal photons is determined by a total phase, acquired by all three propagating photons: the signal, the idler and the pump 2,3 . This is different than conventional interferometry, where the interference pattern is defined solely by the phase of the signal photon. From the interference pattern of the signal photon, it is possible to infer a relative phase of an idler photon. Actual detection of idler photons is not required. This scheme has found its applications in imaging

Characterization and Coherent Control of Spin Qubits with Modulated Electron Beam and Resonator

“…Quantum bits (qubits) are essential components in various areas of quantum science and technology, such as quantum computation, [1,2] data encryption, secure information transmission, [3,4] and quantum metrology and imaging. [5,6] To fully exploit the potential of qubits, it is crucial to perform a comprehensive characterization of these two-level quantum systems and optimize their characteristics. This requires the development of experimental techniques for measuring and controlling the qubit state, as well as theoretical models for describing the qubit DOI: 10.1002/qute.202300207 dynamics.…”