The UK has recently invested over a quarter of a billions pounds into the emerging field of quantum technology, and this has spurred similar investment worldwide. As technological devices become ever smaller, we are quickly approaching the scale where quantum mechanics becomes predominant over classical physics. States of matter (energy, position, momentum, etc.) will become ‘superpositions’ rather than definitive values, and components can become ‘entangled’ over large distances thus affecting each other with no clear physical connection. This could lead to severe malfunctions if we keep pushing classical technology approaches, hence the need to identify ways in which these strange quantum effects can become advantageous instead.

One area is in the field of sensing. Atoms are formed of massive nuclei surrounded by electrons, and thus are sensitive to electric and magnetic fields, gravity and non-inertial forces (accelerations and rotation). We now have the ability to trap and cool atoms within ultra-high vacuum chambers such that we have dense samples of atoms which we can manipulate and measure for long periods of time. Moreover, when atoms are cooled to very low temperatures they begin to exhibit wave-like properties which can be used to form atomic interferometers. This improves measurement precision and is the basis behind modern atomic clocks.   

However, making cold atom sensors is one half of the story. The national quantum technology program aims to unshackle quantum technology from the laboratory. Therefore our atomic sensors need to be compact, integrated and robust enough to function in a variety of different environments. This is a challenging task as cold atom technology is still in the early stages of development and little research has been undertaken to ensure they can work whilst experiencing mechanical vibrations, thermal fluctuations, and sudden jolts. One also needs to add on to this the need for low power operation, small size and weight and simple controls, to make these systems commercially viable.

Our group has been working on these problems for several years, primarily focusing on miniaturising and integrating cold atom sources. We are now moving into exploring methods to make the sensing operation more robust. This will follow two streams of research. 1) Using multiple cold atom source and measuring the difference between their signals. Any external vibration noise is common to both sensors and thus the difference is immune. We are exploring optical fibre based methods to couple these sensors. 2) By shortening the time between measurements, one can reduce the effect of large accelerations and low frequency fluctuations, thus providing a higher dynamic range of measurement. While this can reduce the ultimate performance of the system, it will increase sampling rate and thus allow one to ‘average out’ the noise faster. We will be developing a high speed cold atom source for sensing accelerations and rotations coincidentally using dual atom interferometry.