Cryogenic Atom Chips

Abstract

It is quite remarkable to observe that in 1995, when Weinstein and Libbrecht wrote their seminal article on microscopic atomic traps [1], the very same research group published experimental results on long-lived neutral atom traps in a cryogenic environment [2]. They reported trapping lifetimes of nearly 10 minutes for magnetostatic traps created by centimeter-size superconducting coils. Moreover they claimed that "with a cryogenic system one can use superconducting magnets and SQUID detectors to trap and non-destructively sense spin-polarized atoms". This sentence foresees some of the possibilities of cryogenic atom chips using superconducting materials. Low temperatures and superconductivity do not only offer ultrahigh vacuum conditions and high currents without dissipation. They also open the way to a new class of experiments where ultra-cold atoms will be integrated on a chip together with solid-state devices whose coherent manipulation is only possible at low temperatures. A good example of such a device is a Superconducting Quantum Interference Device (SQUID) coupled to the magnetic moment of the trapped atomic cloud [3]. Other interesting candidates like coplanar waveguide resonators or the nano-electro-mechanical system (NEMS) are also worth mentioning.It took some time after the initial proposal of [1] to develop and operate the first atom chips (see Chapter 1) at room temperature and an even longer time to operate them in cryogenic conditions. The first results on superconducting atom chips were reported at ENS Paris in 2006 [4] and at NTT Basic research labs in 2007 [5]. Many groups in the world are now building experiments along this line of research and exciting developments are expected. The first part of this chapter (Section 10.2) will present a review of the existing experiments on cryogenic chips. We will try to show by which aspects they may be similar to or differ from equivalent roomtemperature setups. In Section 10.3 we will give a few examples of new experiments that could be carried out with cryogenic chips. Atom Chips. Edited by Jakob Reichel and Vladan Vuletić

Ionization channel of continuum lowering in plasmas: effects of plasma screening, electric and magnetic fields

“…It should be noted that circular states of atomic and molecular systems, used in the present work, is an important subject in its own right. They have been extensively studied both theoretically and experimentally for several reasons (see, e.g., [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] and references therein): (a) they have long radiative lifetimes and highly anisotropic collision cross sections, thereby enabling experiments on inhibited spontaneous emission and cold Rydberg gases, (b) these classical states correspond to quantal coherent states, objects of fundamental importance, (c) a classical description of these states is the primary term in the quantal method based on the 1/n-expansion, and (d) they can be used in developing atom chips. In the present paper we used circular states just to get the message across and to stimulate further studies of CL in the ionization channel.…”

3D modeling of magnetic atom traps on type-II superconductor chips

“…the Casimir-Polder force), the spin decoherence of atoms near dielectric bodies, and in the usage of trapped atoms to probe local irregularities of magnetic and electric fields near conductive films. Possible applications of atom chips are in quantum information processing, quantum metrology, quantum optics, high-resolution spectroscopy, atom SQUIDs and interferometers, etc [1][2][3][4][5][6][7][8].…”

“…The chips produce tiny magnetic field configurations which can trap, cool, and manipulate ensembles of ultra-cold atoms in a deep vacuum near solid surfaces [1][2][3][4][5][6]. Trapping neutral atoms having a nonzero magnetic moment is based on the Zeeman effect: depending on the quantum state of an atom with a magnetic moment, the atom's energy either increases or decreases with the magnetic field growth.…”