Quantum sensors: Measuring even more precisely
Date:
March 23, 2022
Source:
University of Innsbruck
Summary:
Two teams of physicists have designed the first programmable quantum
sensor, and tested it in the laboratory. To do so they applied
techniques from quantum information processing to a measurement
problem. The innovative method promises quantum sensors whose
precision reaches close to the limit set by the laws of nature.
FULL STORY ========================================================================== Atomic clocks are the best sensors humankind has ever built. Today,
they can be found in national standards institutes or satellites of
navigation systems.
Scientists all over the world are working to further optimize the
precision of these clocks. Now, a research group led by Peter Zoller, a theorist from Innsbruck, Austria, has developed a new concept that can be
used to operate sensors with even greater precision irrespective of which technical platform is used to make the sensor. "We answer the question of
how precise a sensor can be with existing control capabilities, and give a recipe for how this can be achieved," explain Denis Vasilyev and Raphael Kaubru"gger from Peter Zoller's group at the Institute of Quantum Optics
and Quantum Information at the Austrian Academy of Sciences in Innsbruck.
==========================================================================
For this purpose, the physicists use a method from quantum information processing: variational quantum algorithms describe a circuit of quantum
gates that depends on free parameters. Through optimization routines, the sensor autonomously finds the best settings for an optimal result. "We
applied this technique to a problem from metrology -- the science of measurement," Vasilyev and Kaubru"gger explain. "This is exciting because historically advances in atomic physics were motivated by metrology,
and in turn quantum information processing emerged from that. So, we've
come full circle here," Peter Zoller enthuses. With the new approach, scientists can optimize quantum sensors to the point where they achieve
the best possible precision technically permissible.
Better measurements with little extra effort For some time, it has
been understood that atomic clocks could run even more accurately by
exploiting quantum mechanical entanglement. However, there has been a
lack of methods to realize robust entanglement for such applications.
The Innsbruck physicists are now using tailor-made entanglement
that is precisely tuned to real-world requirements. With their
method, they generate exactly the combination consisting of quantum
state and measurements that is optimal for each individual quantum
sensor. This allows the precision of the sensor to be brought close
to the optimum possible according to the laws of nature, with only a
slight increase in overhead. "In the development of quantum computers,
we have learned to create tailored entangled states," says Christian
Marciniak from the Department of Experimental Physics at the University
of Innsbruck. "We are now using this knowledge to build better sensors." Demonstrating quantum advantage with sensors This theoretical concept
was now implemented in practice for the first time at the University
of Innsbruck, as the research group led by Thomas Monz and Rainer Blatt
now reported in Nature. The physicists performed frequency measurements
based on variational quantum calculations on their ion trap quantum
computer. Because the interactions used in linear ion traps are still relatively easy to simulate on classical computers, the theory colleagues
were able to check the necessary parameters on a supercomputer at the University of Innsbruck. Although the experimental setup is by no means perfect, the results agree surprisingly well with the theoretically
predicted values. Since such simulations are not feasible for all sensors,
the scientists demonstrated a second approach: They used methods to automatically optimize the parameters without prior knowledge. "Similar
to machine learning, the programmable quantum computer finds its optimal
mode autonomously as a high-precision sensor," says experimental physicist Thomas Feldker, describing the underlying mechanism.
"Our concept makes it possible to demonstrate the advantage of quantum technologies over classical computers on a problem of practical
relevance," emphasizes Peter Zoller. "We have demonstrated a crucial
component of quantum- enhanced atomic clocks with our variational
Ramsey interferometry. Running this in a dedicated atomic clock is
the next step. What has so far only been shown for calculations of
questionable practical relevance could now be demonstrated with a
programmable quantum sensor in the near future -- quantum advantage."
The research was financially supported by the Austrian Science Fund FWF,
the Research Promotion Agency FFG, the European Union within the framework
of the Quantum Flagship and the Federation of Austrian Industries Tyrol,
among others.
========================================================================== Story Source: Materials provided by University_of_Innsbruck. Note:
Content may be edited for style and length.
========================================================================== Journal References:
1. Christian D. Marciniak, Thomas Feldker, Ivan Pogorelov, Raphael
Kaubruegger, Denis V. Vasilyev, Rick van Bijnen, Philipp Schindler,
Peter Zoller, Rainer Blatt, Thomas Monz. Optimal metrology with
programmable quantum sensors. Nature, 2022; 603 (7902): 604 DOI:
10.1038/s41586-022- 04435-4
2. Raphael Kaubruegger, Denis V. Vasilyev, Marius Schulte, Klemens
Hammerer,
Peter Zoller. Quantum Variational Optimization of Ramsey
Interferometry and Atomic Clocks. Physical Review X, 2021; 11 (4)
DOI: 10.1103/ PhysRevX.11.041045 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220323125115.htm
--- up 3 weeks, 2 days, 10 hours, 51 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)