Scientists from the Laboratory of cold atoms for the first time NASA measured the condensate Bose — Einstein atoms of rubidium-87 to the ISS in a permanent state of weightlessness (microgravity). As reported in Nature, the microgravity environment allowed us to achieve record characteristics of the condensate: a time of free expansion after switching off the traps exceeded a second, and the effective temperature drops below nanokelvin.
Condensate Bose — Einstein called this state of matter in which a noticeable percentage of atoms is located in the heart of low energy quantum state, or ground state. These atoms behave like a single quantum entity with a common wave function. Condensate Bose — Einstein occurs in a rarefied gas of particles-bosons when they are cooled below a critical temperature. This temperature depends on the fundamental physical constants (Planck’s constant, Boltzmann’s constant), it is also inversely proportional to the mass of a single boson and m is directly proportional to n2/3, where n is the concentration of bosons in the gas.
Unlike other macroscopic quantum phenomena related to Bose-condensation of superfluidity and superconductivity is a comprehensive study which began in the first half of the twentieth century, controlled to the condensation of clouds of individual atoms was a difficult task. Atoms are much more massive Cooper pairs responsible for superconductivity, so the critical temperature of condensation in an atomic gas by orders of magnitude lower than the transition temperature of the metal in the superconducting state.
For the first time, scientists from the University of Colorado were able to obtain a condensate of atoms of rubidium-87 in 1995 with invented in the 1980s, the techniques of laser cooling and magnetic evaporative cooling. Condensation occurred at a temperature of about 170 nanokelvin. A few months later in the same year, a group of scientists from MIT created a Bose condensate of atoms of sodium-23 and including the demonstrated quantum interference between two different condensates.
Condensation is extremely sensitive to the influence of gravity, which can dislodge the atoms from the trap and prevent effective cooling. This sensitivity allows the use of a condensate of Bose — Einstein inertial accelerometers with a sensitivity less than 10-3 g. The development and improvement of such sensors is extremely convenient to carry out in microgravity (weightlessness), which also increases the number of atoms in the condensate and further lowering its temperature.
In the past scientists have made great efforts to compensate for the Earth’s gravitational field acting on the condensate. As a rule, these decisions were quite cumbersome and required the use of special lifts, creating ultrasonography cameras 10-meter height or durable plants, which freely fell from 120-meters high inside the tower falls (which is located in the center of applied space technology and microgravity (ZARM) of the University of Bremen) and can withstand overload up to 50g. In one recent experiment, scientists studied a condensate of rubidium-87 in zero gravity using the placement of the installation on Board meteorological MAIUS-1, which rose to a height of more than 240 miles and has been in free fall for about six minutes. The next logical step in this direction is the development of a full experimental setup for the ISS (i.e. low earth orbit) for long-term study of condensate in microgravity.
Scientists from the Laboratory of cold atoms of NASA under the leadership of Robert Thompson (Robert J. Thompson) demonstrated the results of measurements of the condensate in a fully Autonomous installation EXPRESS, which was delivered to the ISS in 2018, and then is deployed to and running with the help of astronauts. The condensate obtained on the ISS in the current experiment demonstrates a number of features: it consists of a larger number of atoms contains atoms in nonmagnetic state and time extensions to the free state for the condensate is greater than the second.