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EETE JUN 2014

UK sees opportunities for quantum sensor and clock developments By Nick Flaherty The UK believes it has a major advantage in the development of quantum clocks and sensors for navigation. The UK is becoming overly reliant on GNSS and GPS signals for timing, and new sources of accurate timing are being investigated for military applications. These developments in quantum technologies for clocks are also opening up opportunities in sensors using the same technologies. The quantum research can deliver stability and accuracy four orders of magnitude better than other systems, says Stephen Timms, fellow at the UK DSTL which is part of the Ministry of Defence. This will allow tradeoffs for smaller, chip scale devices for defence, space and even consumer applications. “Whilst the most immediate applications are in the defence field, future quantum navigation technologies could also have significant civilian applications across a wide variety of activities, The quantum opportunities and timescales (source: DSTL) covering high frequency trading, network synchronisation, robust and ubiquitous navigation, geo-surveying and mineral prospecting,” said Bob Cockshott, Positioning, Navigation and Timing expert at NPL. “With the first applications potentially ready for market in five years, now is the critical time to consider the opportunities provided by quantum.” The UK government has taken more interest in these opportunities. “Among many promising areas, quantum technologies may bring game-changing advantages to future timing, sensing and navigation capabilities that could support multi-billion pound markets in the UK and globally,” said Rt Hon David Willetts, Universities and Science Minister. “Much of this is at an early stage of development. Scientists need the freedom to explore the most exciting research directions, and we also need to be on the lookout for early commercialisation opportunities.” The UK provides 7% of the world market (estimated at $490 billion in 2013) in sensor components and sensor systems says DSTL and growth in the sensors market appears to have been unaffected by the worldwide recession, it is increasing at 8-11% per year. Researchers have already been able to build wafer level quantum sensors that confine a cloud of ions, confine them and cool them down with a semiconductor laser and diffraction gratings so that the quantum states become entangled. Tiny changes in acceleration can be detected by the entangled ions, providing an accelerometer, gravity detector or highly accurate atomic clock. A team at the UK’s national Physical Laboratory (NPL) in London are using a standard semiconductor micromachined (MEMS) process to build the channels and cantilevers with gold electrodes that confine the ion cloud on a series of chips on a four inch wafer with the required consistency. MEMS lends itself to building these kinds of sensors as a heating effect of the RF signals used to measure the state of the ions is significantly reduced. The next step is to use platinum electrodes to further reduce the heating effect of the RF used to contain the ions. New technologies for ultra high vacuum(UHV) packaging are being developed along with investigating the use of graphene for less noisy electrodes. Prof Mark Fromhold at the University of Nottingham is working on new production techniques for grapheme to reduce the power consumption of such devices by five orders of magnitude. This comes from creating smoother electrodes than gold or platinum to reduce the power needed to confine the ion cloud. “It’s a bit like electronics in the valve era, a cold atom sensor is a big, room sized device,” said Prof Fromhold. “Graphene can reduce the power by 100,000 and enable miniaturisation and integration of cold atoms on existing devices.” Other researchers at the University of Southampton are developing an ion trap on chip with UHV, using packaging materials such as aluminosilicate ‘gorilla’ glass that is also used for phone and tablet screens. A team at NPL has been able to capture cold ions using doped silicon wafers with segmented electrode structures. These chips have been mounted in a standard semiconductor package in an ultra high vacuum package with direct laser access for cooling and probing the ions. The next step is to use semiconductor lasers inside the package with the new packaging materials to create clocks with accuracy 2 to 3 orders of magnitude greater than today’s caesium-based atomic clocks, but in a chip package. The cold ion approach is also being used for a quantum interferometer that acts as an inertial navigation system. Prof Ed Hinds and his team at Imperial College in London are using laser light to track how atoms move in free fall. A MEMS cold ion chip carrier. The ion trap chip carrier with laser measurement. 10 Electronic Engineering Times Europe June 2014 www.electronics-eetimes.com


EETE JUN 2014
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