P. Goy

Instrumentation for millimeter-wave magnetoelectrodynamic investigations of low-dimensional conductors and superconductors

We describe instrumentation for conducting high sensitivity millimeter-wave cavity perturbation measurements over a broad frequency range (40–200 GHz) and in the presence of strong magnetic fields (up to 33 T). A millimeter-wave vector network analyzer (MVNA) acts as a continuously tunable microwave source and phase sensitive detector (8–350 GHz), enabling simultaneous measurements of the complex cavity parameters (resonance frequency and Q value) at a rapid repetition rate (∼10 kHz). We discuss the principle of operation of the MVNA and the construction of a probe for coupling the MVNA to various cylindrical resonator configurations which can easily be inserted into a high field magnet cryostat. We also present several experimental results which demonstrate the potential of the instrument for studies of low-dimensional conducting systems.

Shot-noise detection of ultrasound-tagged photons in ultrasound-modulated optical imaging

We propose a new detection method for ultrasound-modulated optical tomography that allows us to perform parallel speckle detection with optimum shot-noise sensitivity, using a CCD camera. Moreover, we show that making use of a spatial filter system allows us to fully filter out speckle decorrelation noise. This method is confirmed by a test experiment.

Determination of the Gyrotropic Characteristics of Hexaferrite Ceramics From 75 to 600 GHz

The work reported in this paper is in support of applications of ferrites in measurement systems operating at frequencies in the range 100-600 GHz. Measurements of the magneto-optical characteristics of selected grain-oriented hexaferrite ceramics from 75 to 600 GHz are described; a quasi-optical transmissometer driven by a multiband vector-network-analyser is used to provide the required high dynamic range, spectral-resolution, and scan-speeds. The implications of the results of the measurements are examined.

Millimetre resonances in Na Rydberg levels detected by field ionization: quantum defects and Stark-effect studies

Transitions between Na Rydberg levels induced by microwave radiation in the millimetre range have been observed by field-ionization detection. These transitions, whose frequencies yield the quantum defects of the levels, appear sensitive to very weak electric field perturbations as expected. Observations of field-induced forbidden transitions and of Stark shifts in fields down to 50 mV cm-1 are reported.

The two-photon Rydberg atom micromaser

A Rydberg atom maser operated on a two-photon degenerate atomic transition is discussed. This device combines two interesting features: it is a quantum oscillator working on an intrinsically nonlinear effect and it is a micromaser, with only a few atoms and a few tens of photons at a time in the cavity. The reasons why Rydberg atom-superconducting cavity systems are well adapted for two-photon maser studies are discussed, and the main properties of the device are analyzed by comparing it to Rydberg masers operating on one-photon transitions. >

High-resolution two-photon millimetre spectroscopy in sodium Rydberg states: possible applications to metrology

The authors have observed very narrow two-photon millimetre resonances in sodium, corresponding to nS to (n+1)S transitions (principal quantum number n ranging from 32 to 40). The linewidth, of the order of 10 kHz for frequencies around 100 GHz, is transit-time limited. The variation with n of the quantum defects in the nS series is studied. The precision of the experiments can still be improved and applications to metrology and to a direct frequency determination of the Rydberg constant are possible.

Electromagnetic properties of polycrystalline diamond from 35 K to room temperature and microwave to terahertz frequencies

Dielectric resonators are key components for many microwave and millimeter wave applications, including high-Q filters and frequency-determining elements for precision frequency synthesis. These often depend on the quality of the dielectric material. The commonly used material for building the best cryogenic microwave oscillators is sapphire. However, sapphire is becoming a limiting factor for higher frequency designs. It is, then, important to find new candidates that can fulfill the requirements for millimeter wave low noise oscillators at room and cryogenic temperatures. These clocks are used as a reference in many fields, such as modern telecommunication systems, radio astronomy (very-long-baseline interferometry), and precision measurements at the quantum limit. High resolution measurements were taken of the temperature-dependence of the electromagnetic properties of a polycrystalline diamond disk at temperatures between 35 and 330 K at microwave to submillimeter wave frequencies. The cryogenic measu...

Free Space Vector Transmission-Reflection from 18 to 760 GHz

In millimeter and submillimeter waves, propagation in free space is easily obtained with reasonable size quasioptical components. Quasi-plane wave transmission-reflection measurements have been observed with yector detection through various samples including dielectrics and absorbers, in the extended frequency interval from 18 to 760 GHz. The calibration procedure is extremely simple, and most of spurious effects, like parasitic reflexions, can be characterized and eliminated in the time domain.

Inter-laboratory comparison of reflection and transmission measurements in WR-06 waveguide (110 GHz to 170 GHz)

This paper describes an exercise that was undertaken recently to compare reflection and transmission measurements in rectangular metallic waveguide from 110 GHz to 170 GHz (i.e. in the WR-06 waveguide size). The comparison involved making measurements on four devices fitted with ‘precision’ MIL-DTL-3922-67D style flanges. These devices were circulated amongst the nine organizations that chose to participate in the exercise. The comparison took place between August 2008 and September 2009. Results from the exercise are presented in graphical form along with a statistical summary showing average variability for the measurements. The authors believe this is the first time that such a comparison of measurements has been made at these frequencies. These results therefore provide a benchmark for the current state-of-the-art for measurements made in waveguide at these frequencies.

Millimetre wave response of α-(BEDT-TTF)2NH4Hg(ScN)4

Abstract We present the results of a study of the millimetre-wave response of the organic metal α-(BEDT-TTF) 2 NH 4 Hg(SCN) 4 , between 500 mK and 4.2 K and in magnetic fields of up to 17 T. Two relatively broad features are interpreted as a two dimensional (2D) cyclotron resonance (CR) with a CR mass m 2D CR = 1.35 ±0.1 m e , and a 1D CR with CR mass m 1 D CR = 0.85 ±0.05 m e . Conduction electron spin resonance and magnetic quantum oscillations are also observed. Analysis of the quantum oscillations yields an effective mass of m RF * = 2.7 ± 0.2 m e