The mysterious phenomenon of “spooky motion at a distance” that once worried Einstein may soon become as common as the gyroscopes used to measure acceleration in smartphones. A recent study Nature Photonics showed that quantum entanglement significantly improves the accuracy of sensors that can be used for non-GPS navigation.

“By using entanglement, we increase both the precision of the measurement and the speed at which we can make the measurement,” said Zheshen Zhang, associate professor of electrical and computer engineering at the University of Michigan and co-author of the study. The experiments were conducted at the University of Arizona, where Zhang was working at the time.

Optomechanical sensors measure forces that interfere with a mechanical sensing device that acts in response. This motion is then measured using light waves. In this experiment, the sensors were membranes that acted like drum heads that vibrated after being shaken. Optomechanical sensors can act as accelerometers that can be used for inertial navigation on a planet without GPS satellites or as a person moving across different floors within a building.

Quantum entanglement could make opto-mechanical sensors more accurate than inertial sensors currently in use. It could also allow opto-mechanical sensors to look for very subtle forces, such as detecting the presence of dark matter. Dark matter is invisible matter in the universe that is believed to form five times more mass than we can feel with light. It would pull the sensor by the force of gravity.

Here’s how entanglement improves opto-mechanical sensors:

Optical-mechanical sensors are based on two synchronized laser beams. One of them bounces off the sensor, and any movement in the sensor changes the distance the light travels on its way to the detector. This difference in distance traveled becomes apparent when the second wave is superimposed on the first wave. If the sensor is stationary, the two waves coincide perfectly. However, if the sensor moves, they create an interference pattern because the peaks and troughs of their waves offset each other in places. This model shows the size and speed of vibration in the sensor.

Generally, in interferometry systems, the farther the light travels, the more accurate the system. The Laser Interferometer Gravitational-Wave Observatory, the most sensitive interferometry system on the planet, sends light on 8-kilometer journeys. But it will not fit on a smartphone.

To achieve the high sensitivity of miniature opto-mechanical sensors, Zhang’s team investigated quantum entanglement. Instead of splitting the light once to reflect from one sensor and one mirror, they split each beam a second time so that the light is reflected from two sensors and two mirrors. Dalziel Wilson, a professor of optical sciences at the University of Arizona, created the membrane devices together with doctoral students Aman Agrawal and Christian Pluchar. Just 100 nanometers or 0.0001 millimeters thick, these membranes move in response to very small forces.

Doubling the sensors improves accuracy because the dice have to vibrate in sync with each other, but entanglement adds an extra layer of coordination. Zhang’s group created the entanglement by “squeezing” the laser light. In quantum mechanical objects, such as the photons that make up light, there is a fundamental limit to which a particle’s position and momentum can be known exactly. Since photons are also waves, this means the phase (where it oscillates) and amplitude (how much energy it carries) of the wave.