Invited Speakers

Space Rubidium Atomic Frequency Standard for BeiDou Navigation Satellite System

 

The lecture outlines development of the BDS system and its space rubidium atomic frequency standard (RAFS). Status of the BDS system was briefly introduced, and main features of the RAFS developed by WIPM were described in detail. Frequency stability per day of the RAFS units was within 2.0~5.0E-14, comparable with those used in GPS Block IIR and Galileo satellites. Further improvement of the RAFS is being performed at WIPM.

Deep Space Atomic Clock (DSAC) for a Technology Demonstration Mission

 

There are many different atomic clock technologies but few meet the demanding performance, reliability, size, mass, and power constraints required for space based navigation applications. JPL is currently developing a mercury trapped ion clock [1,2] for a NASA Technology Demonstration Mission (TDM) referred to as DSAC (Deep Space Atomic Clock) [3]. A one year flight demonstration as a hosted payload is planned following a 2016 launch. Ion clock development, status, and a brief mission overview will be presented.

Testing the Isotropy of Space by Comparing Two co-Rotating Precision Quartz Frequency Standards

 

In an attempt to uncover experimental evidence of Lorentz invariance violation, this work undertakes measurements of acoustic oscillations in precision quartz oscillators designed for stable frequency generation. Using standard robust room temperature technology, set rotating at a fraction of a Hertz, the isotropy of inertial masses of neutrons has been verified to six orders of magnitude greater precision than any previous laboratory experiment, and an order of magnitude better than previous astrophysical experiment. The theories of Quantum Mechanics and General Relativity have had great experimental success, but coexist as two incompatible theories. However, different theoretical frameworks of unification allow or even predict small Lorentz invariance violation, that is, a violation of the paradigm that experimental results do not depend on orientation in space or velocity of the laboratory apparatus. We discuss how future cryogenic quartz oscillators may make an additional four orders of magnitude improvement possible. This will open up the potential for improved tests of Lorentz invariance of neutrons, protons, electrons and photons.

ZIF-Coupled Resonant Sensors

 

This work reports on zeolitic imidazolate framework (ZIF)-coupled microscale resonators for highly sensitive and selective gas detection. The combination of microscale resonators and nanoscale materials simultaneously permits the benefit of larger capture area for adsorption from the resonator and enhanced surface adsorption capacity from the nanoscale ZIF structure. The ZIF-coupled resonators demonstrated sensitivity improvement up to 150 times over a bare silicon resonator with identical dimensions, and real-time adsorption measurements of ZIFs revealed different adsorption time constants for IPA and CO2. Progress and challenges of resonant sensing will also be summarized.

ALD-Enabled NanoElectroMechanical Systems

 

Atomic Layer Deposition (ALD) and Molecular Layer Deposition (MLD) can be effectively used to deposit custom-designed, multi-material layers with atomic resolution on any micro- or nano-scale device surface. The nano-scale ALD/MLD coating can protect the devices from electrical short, charge accumulation, moisture-induced adhesion, wear, corrosion, creep, fatigue or anodic oxidation during short-term prototyping or long-term product life. The nano- and micro-electro-mechanical systems (N/MEMS) community has been looking for effective antistiction and environmental protection coatings for many years.

Ultimate and practical limits to micro- and nanomechanical frequency-shift-based sensing

 

Frequency-shift sensing has emerged as the basis for important new applications in metrology em-ploying micro- and nano- electromechanical systems (MEMS/NEMS). Prominent among these are new approaches to magnetic resonance, radiation detection, and chemical and biological analyte de-tection by inertial mass sensing in gas, liquid, and vacuum. I will briefly review recent achievements in these areas, and then describe the physics underlying the ultimate and practical limits of frequency-shift sensing with MEMS/NEMS.

Electronically Stabilized Time and Frequency Distribution Over Optical Fiber - an Overview

 

This presentation is an overview of the technology developed at AGH University of Science and Technology for time and RF-frequency distribution over optical fibers. The main part of the presentation is a systematic and organized description of the ELSTAB solution, spread in pieces in our previous papers. Some new achievements however, not published till now, are also presented.

GPS Timing Service

 

The Global Positioning System (GPS) will celebrate the 20th anniversary of achieving full operational capability (FOC) on April 27, 2015.  GPS has revolutionized the world’s ability to precisely position and synchronize activities.  The GPS timing service is often overlooked, but it is critical for many industries such as telecommunication, financial, scientific and the power industry.  This paper provides an overview of how the GPS timing service operates its performance, USNO’s role and a historical look at impact of the GPS timing service.

 

Stable Time and Frequency Transfer in the Atacama Large Millimeter Array

 

The ALMA (Atacama Large Millimeter Array) is a single radio telescope of advanced design, composed of sixty-six high-precision 12-meter antennas located on the Chajnantor plateau in the Atacama Desert of Northern Chile. This paper will describe the ALMA LO and timing system, which required a 1st local oscillator with 22 femtosecond precision over 15 km.

Dark Matter Search with Atomic Clocks and GPS

 

The cosmological applications of atomic clocks so far have been limited to searches of the uniform-in-time drift of fundamental constants. We argue that a transient in time change of fundamental constants can be induced by dark matter objects that have large spatial extent, and are built from light non-Standard Model fields. The stability of this type of dark matter can be dictated by the topological reasons. A correlated network of atomic clocks such as atomic clocks onboard satellites of the GPS constellation, can be used as a powerful tool to search for the topological defect dark matter. In other words, one could envision using GPS as a 50,000 km-aperture dark-matter detector.

Relativistic Geodesy with Clocks

 

The recent progress in optical atomic clocks and in long-distance frequency transfer by optical fiber together pave the way for using measurements of the gravitational frequency redshift for geodesy. The remote comparison of frequencies generated by calibrated clocks will allow for a purely relativistic determination of differences in gravitational potential and height between stations on Earth surface (chronometric leveling). Experiments for the proof of concept for this technique are currently in preparation at Leibniz Universität and Physikalisch-Technische Bundesanstalt (PTB). If successful, the technique could on the long run provide the basis for an atomic height reference and a relativistic geoid definition.

 

Enhancing Clocks with Collective Effects: Spin Squeezing and Superradiance

 

Precision measurements have leveraged the ability to completely control both the external and internal degrees of freedom of atoms. We will present our work exploring how to now create and control interactions between atoms to generate entanglement and correlations useful for further advancing precision measurements with laser-cooled atoms. We demonstrate a factor of 10 reduction in phase variance with respect to the standard quantum limit on phase estimation. We also demonstrate a superradiant laser that operates with <1 photon inside the cavity and will discuss how this may one day lead to millihertz linewidth lasers.