First Macroscopic Quantum Entanglement At Room Temperature Achieved

Paul Klimov, a graduate student at the Institute for Molecular Engineering, adjusts the intensity of a laser beam during an experiment. University of Chicago

November has been a great month for quantum entanglement fans. Not only was entanglement proven to be a fact of nature, but the first quantum computer code was written on an entangled system as well. Now, scientists from the University of Chicago were able to obtain a quantum entanglement state at room temperature in a macroscopic (relatively large) object. Macroscopic objects are expected to obey exclusively classical physics, so this experiment is a big deal. 

The team has used infrared lights to align the magnetic states of electrons and nuclei in a wafer of silicon carbide (SiC), a material used in semiconductor electronics. The infrared light orders thousands of atoms and the researchers used short magnetic pulses (akin to those used in MRI machines) to entangle them.

Entangled particles cannot be described independently and their properties (such as energy, momentum, and so on) are all connected. Even if they are separated, they remain linked; changes to one will immediately affect the other particles in the entangled system. To create entanglement particles, the starting point is always a state with a high degree of order, such as if all the atoms are made to act like tiny magnets and point in the same direction. Creating a high-order state requires a lot of energy as the universe doesn’t like things to be tidy. The larger the number of particles, the more difficult it is to entangle them.

"The macroscopic world that we are used to seems very tidy, but it is completely disordered at the atomic scale," said lead author Paul Klimov from the University of Chicago in a statement. "The laws of thermodynamics generally prevent us from observing quantum phenomena in macroscopic objects." 

To avoid thermodynamics problems, scientists have previously ultra-cooled materials to a temperature around absolute zero or used intense magnetic fields to keep things ordered. The new technique doesn’t need these approaches. The procedure allowed for the formation of the entangled state in a 40 micrometer-cubed volume (about the size of a red blood cell) at room temperature and using only a modest magnetic field.

There are far-reaching consequences to having a room-temperature macroscopic entangled system. Macroscopic entanglement will play a pivotal role in quantum computing as well as quantum sensors able to go beyond the sensitivity of current ones. The discovery also goes beyond physics and material science. For example, SiC is non-toxic so it could be used in biomedical research inside the body. The next step for this research is to create entangled states on different SiC chips. 

A paper describing the research is published by Science Advances


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