Quantum clocks are shrinking thanks to new technologies developed by Sensors and Timing at the University of Birmingham’s UK Quantum Technology Centre
Working with and partly funded by the UK’s Defense Science and Technology Laboratory (Dstl), a team of quantum physicists has devised new approaches that not only reduce the size of their clock, but also make it robust enough to be transported out of the lab and used in the real world”.
Quantum or atomic clocks are widely seen as essential for increasingly precise approaches in areas such as worldwide online communications, navigation systems or global stock trading, where fractions of a second can make a huge economic difference. Atomic clocks with optical clock frequencies can be 10,000 times more accurate than their microwave counterparts, opening up the possibility of redefining the standard unit of measurement (SI).
Even more advanced optical watches may one day make a significant difference to both everyday life and basic science. By allowing longer periods between resynchronization needs than other clock types, they provide increased resiliency for the national timing infrastructure and unlock future positioning and navigation applications for autonomous vehicles. The unparalleled accuracy of these clocks can also help us look beyond standard physical models and understand some of the more mysterious aspects of the universe, including dark matter and dark energy. Such clocks will also help answer fundamental physics questions, such as whether fundamental constants are really “constants” or whether they vary with time.
Leading researcher Dr. Yogeshwar Kale said: “The stability and accuracy of optical clocks make them essential for many future information and communication networks. Once we have a system ready to be used outside the laboratory, we can use them, for example Earth navigation networks, where all these watches are connected via fiber optics and begin to communicate with each other.Such networks will reduce our dependence on GPS systems, which can sometimes fail.
“These transportable optical clocks will not only help improve geodetic measurements – the fundamental properties of the Earth’s shape and variations in gravity – but will also serve as precursors to monitor and identify geodynamic signals such as earthquakes and volcanoes at early stages. »
Although these quantometers are developing rapidly, the main obstacles to their use are their size – current models come in a van or car trailer and weigh around 1500 liters – and their sensitivity to environmental conditions that limit their transport between different locations.
The Birmingham, UK-based Quantum Technology Hub Sensors and Timing team has developed a solution that addresses both of these challenges in a package that is an approximately 120 liter ‘box’ weighing less than 75 kg. The book is published in Quantum Science and Technology.
A Dstl spokesperson added: “Dstl views optical clock technology as a key enabler for future Defense Department capabilities. These types of clocks have the potential to shape the future by providing increased resilience to national infrastructures and changing the way communications and sensor networks are designed. With support from Dstl, the University of Birmingham has made significant progress in miniaturizing many subsystems of an optical grating clock and in doing so has overcome many significant technical challenges. We look forward to seeing what further progress they can make in this area. exciting and fast developing field.”
Clocks work by using lasers to produce and then measure quantum oscillations in atoms. These oscillations can be measured with great precision and from the frequency it is also possible to measure the time. One challenge is to minimize external influences on the measurements, such as mechanical vibrations and electromagnetic interference. To do this, the measurements must take place in a vacuum and with a minimum of external interference.
At the heart of the new design is an ultra-high vacuum chamber, smaller than anything still used in quantum time measurement. This chamber can be used to trap atoms and then cool them very close to the value of “absolute zero” so that they reach a state where they can be used for precision quantum sensors.
The team demonstrated that they could trap nearly 160,000 ultracold atoms in the chamber in less than a second. In addition, they demonstrated that they could transport the system for 200 km before setting it up to be ready to take measurements in less than 90 minutes. The system was able to survive a temperature increase of 8 degrees above the ambient temperature during the trip.
Dr. Kale added: “We were able to demonstrate a robust and resilient system that can be transported and installed quickly by a single skilled technician. This brings us closer to using these high-precision quantum instruments in harsh settings outside of a laboratory environment.”