We study the spectral signatures and coherence properties of radiofrequency dressed hyperfine Zeeman sub-levels of 87Rb. Experimentally, we engineer combinations of static and RF magnetic fields to modify the response of the atomic spin states to environmental magnetic field noise. We demonstrate analytically and experimentally the existence of ‘magic’ dressing conditions where decoherence due to electromagnetic field noise is strongly suppressed. Building upon this result, we propose a bi-chromatic dressing configuration that reduces the global sensitivity of the atomic ground states to low-frequency noise, and enables the simultaneous protection of multiple transitions between the two ground hyperfine manifolds of atomic alkali species. Our methods produce protected transitions between any pair of hyperfine sub-levels at arbitrary (low) DC-magnetic fields.
Gravitational Waves (GWs) were observed for the first time in 2015, one century after Einstein predicted their existence. There is now growing interest to extend the detection bandwidth to low frequency. The scientific potential of multi-frequency GW astronomy is enormous as it would enable to obtain a more complete picture of cosmic events and mechanisms. This is a unique and entirely new opportunity for the future of astronomy, the success of which depends upon the decisions being made on existing and new infrastructures. The prospect of combining observations from the future space-based instrument LISA together with third generation ground based detectors will open the way towards multi-band GW astronomy, but will leave the infrasound (0.1 Hz to 10 Hz) band uncovered. GW detectors based on matter wave interferometry promise to fill such a sensitivity gap. We propose the European Laboratory for Gravitation and Atom-interferometric Research (ELGAR), an underground infrastructure based on the latest progress in atomic physics, to study space-time and gravitation with the primary goal of detecting GWs in the infrasound band. ELGAR will directly inherit from large research facilities now being built in Europe for the study of large scale atom interferometry and will drive new pan-European synergies from top research centers developing quantum sensors. ELGAR will measure GW radiation in the infrasound band with a peak strain sensitivity of 3.3×10-22/√Hz at 1.7 Hz. The antenna will have an impact on diverse fundamental and applied research fields beyond GW astronomy, including gravitation, general relativity, and geology.
Our paper AEDGE: Atomic Experiment for Dark Matter and Gravity Exploration in Space has just been accepted in EJP!
We propose in this White Paper a concept for a space experiment using cold atoms to search for ultra-light dark matter, and to detect gravitational waves in the frequency range between the most sensitive ranges of LISA and the terrestrial LIGO/Virgo/KAGRA/INDIGO experiments. This interdisciplinary experiment, called Atomic Experiment for Dark Matter and Gravity Exploration (AEDGE), will also complement other planned searches for dark matter, and exploit synergies with other gravitational wave detectors. We give examples of the extended range of sensitivity to ultra-light dark matter offered by AEDGE, and how its gravitational-wave measurements could explore the assembly of super-massive black holes, first-order phase transitions in the early universe and cosmic strings. AEDGE will be based upon technologies now being developed for terrestrial experiments using cold atoms, and will benefit from the space experience obtained with, e.g., LISA and cold atom experiments in microgravity.
Our ELGAR proposal to build a ground-based detector for Gravitational Waves has been featured in PhysicsWorld.com: “Physicists from across Europe have revealed plans for a huge underground gravitational-wave observatory that, if funded, could be operational by the mid-2030s. The European Laboratory for Gravitational and Atom-interferometric Research (ELGAR) could be located in either France or Italy and would cost around €200m to build. Those involved in the project have now applied for European funding to carry out a detailed design and costing for the facility.”
We have just published on https://arxiv.org/abs/1908.11785 a white paper on the scientific motivation for future space tests of the equivalence principle, to explore some of the big questions in physics (e.g. Equivalence Principle, Dark Matter and Gravitational Waves) using matter-wave interferometry, especially in space.
We discuss two possible mission scenarios, one based on quantum technologies, the other on electrostatic accelerometers, that could reach that goal are briefly discussed. We propose experiments to test the universality of free fall, at the level of 10−17 or better.
This approach permits much finer adjustments of the beam direc- tion and position when compared to other beam steering techniques of the same mechanical precision. This results in a much increased precision, accu- racy and mechanical stability. A precision of better than 5μrad and 5 μm is demonstrated, resulting in a resolution in coupling efficiency of 0.1%. To- gether with the added flexibility of an additional beam steering element, this allows a great simplification of the design of the fiber coupler, which normally is the most complex and sensitive element on an optical fiber breadboard. We demonstrate a fiber to fiber coupling efficiency of more than 89.8%, with a stability of 0.2% in a stable temperature environment and 2% fluctuations over a temperature range from 10C to 40C over a measurement time of 14 hours. Furthermore, we do not observe any non-reversible change in the coupling efficiency after performing a series of tests over large temperature variations. This technique finds direct application in proposed missions for quantum experiments in space, e.g. where laser beams are used to cool and manipulate atomic clouds.
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του
κ. Saurabh Pandey
(Σύμφωνα με το άρθρο 41 του Ν. 4485/2017)
Την Παρασκευή 12 Ιουλίου 2019 και ώρα 10:00 στην αίθουσα Τηλεεκπαίδευσης στο κτήριο Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορα του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Saurabh Pandey με θέμα:
«Guided Matter-Wave Interferometry»
Atom interferometry is an extremely sensitive and accurate means of measuring time, gravity, rotation, acceleration, magnetic gradients, and even fundamental physical constants. In particular for rotation sensing, these atomic systems are 10 billion times more sensitive than the optical gyroscopes, for an equal area of the interferometer loop. For practical applications such as satellite-free navigation, the ultracold atom based gyroscopes have to become portable and compact, without compromising their sensitivity. This can be achieved by trapping and manipulation of ultracold atoms in smooth, area-enclosing waveguides. A major challenge, so far, has been the lack of ability to guide the trapped atomic wave-packets over long distances at relatively high speeds.
I will present excitation-free transport of Bose-Einstein condensates (BECs) at hypersonic speeds in magnetic time-averaged adiabatic potential (TAAP) rings traps. For the first time, matter-waves are transported for a record distance of 40 cm at hypersonic speeds without detecting any extra excitation when compared to the static case. The extreme smoothness of TAAP rings is demonstrated via the propagation of ultracold 87Rb atoms in ring waveguides. In addition, I studied atom optics with moving BECs in flat ring waveguides, to enable long distance guiding, and ultralow temperatures of the trapped atoms. I implemented an optimal cooling technique to achieve compact BEC guiding for seconds, and the effective BEC interaction energy was lowered by a factor of 30. These demonstrations provide a new platform to realize highly sensitive, miniaturized cold-atom-based gyroscopes, and investigate fundamental questions.