Quantum Entanglement Could Boost Accuracy of Accelerometers and Sensors of Dark Matter, Study Says

A new study reveals that quantum entanglement has the capacity to significantly boost the precision and accuracy of sensors that could operate without the help of a GPS.

Quantum Entanglement Capacities

Zheshen Zhang, a co-author of the study and associate professor of electrical and computer engineering from the University of Michigan, notes that by exploiting quantum entanglement, both speed of measurement taking and measurement sensitivity can be enhanced. The study was published in Nature Photonics.

As per EurekAlert, quantum entanglement could enable higher accuracy for optomechanical sensors compared to currently-used inertial ones. It could also help optomechanical sensors detect forces that are faint and subtle.

These optomechanical sensors gauge forces that end up disturbing the device and triggering a response. Such motion is then measured through light waves.

In the recent experiment, membranes served as sensors. They act like "drum heads" that end up vibrating after being pushed.

Optomechanical sensors can also work as accelerometers. These devices could be helpful for inertial exploration across planets where GPS satellites are not present or inside a building where a person explores different floors.

As mentioned earlier, quantum entanglement has the capacity to enable optomechanical sensors to pick up subtle forces. This may include dark matter, which is invisible matter that is thought to account for five times more of the light-sensed mass of the universe. With gravitational force, the signal may tug the sensor.

How Quantum Entanglement Boosts Accuracy

As regards the manner how the phenomenon boosts precision, Phys reports that optomechanical sensors depend on two laser beams that are synchronized. One of the beams gets reflected from the sensor. Any sensor movement alters the distance traveled by light toward the detector. This distance difference appears when the first wave gets overlapped by the second one.

If the optomechanical sensor is still, it would mean that there is perfect alignment of the two waves. However, if there is movement, an interference pattern gets created as the waves' troughs and peaks cancel out each other. Such a pattern determines the speed and size of the sensor's vibrations.

While farther light travel is associated with higher accuracy in interferometry systems, the technology cannot fit inside a smartphone.

To welcome boosted accuracy in optomechanical sensors that are smaller, the team looked into quantum entanglement. Instead of splitting light for it to bounce off a mirror or sensor, they split the beams a second time. This enabled the light to bounce off two mirrors and two sensors.

This doubling boosted the accuracy, as such membranes should have vibrated synchronously. However, quantum entanglement offers an additional level of coordination.

The team created quantum entanglement by "squeezing" laser light. Yi Xia, a co-author of the study and a fresh Ph.D. graduate from the lab of Zhang at the University of Arizona, notes that the squeezing helps in redistributing uncertainty. Hence, the component that is squeezed gets more accurately known, while the anti-squeezed components carry higher uncertainty. In light that is squeezed, photons get more closely linked to each other.

Because of the link between the two entangled beam fluctuations, the phase measurement uncertainties were also correlated. Because of this, the team was able to generate 40% more accurate measurements compared to two beams that were unentangled. Moreover, they could do it 60% faster.

The next step for them would be to allow the system to work on miniature scales. Phys further notes that they can already add a source of squeezed light to a chip that is roughly 0.5 centimeters on a side.

In one or two years, the researchers expect to have a prototype chip that has waveguides, inertial sensors, beam splitters, and squeezed-light source.

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