MIT researchers use quantum computing to observe entanglement

MIT researchers use quantum computing to observe entanglement

For the first time, researchers from MIT, Caltech, Harvard University and elsewhere have sent quantum information through a quantum system in what could be understood as traversing a wormhole. Although this experiment did not create a disruption of physical space and time in the way we might understand the science fiction term “wormhole”, the experiment’s calculations showed that qubits traveled from one entangled particle system to another in a gravity pattern. . This experiment performed on Google’s Sycamore quantum processor device opens doors for future experiments with quantum computers to probe ideas from string theory and gravitational physics.

“The simulation of tightly interacting quantum systems, such as those that arise in quantum gravity, is one of the most exciting applications of quantum computers,” says Daniel Harlow, Jerrold R. Zacharias Associate Professor of Physics in Career Development and researcher at MIT. Nuclear Science Laboratory (LNS) which works with David Kolchemeyer, one of the main authors of the book. “It’s a promising first step.”

In a new article from Nature, a team of physicists, including the MIT Center for Theoretical Physics (CTP) and LNS researchers Kolchmeyer and Alexander Zlokapa, present results on a pair of quantum systems that behave analogously to a traversable wormhole.

A wormhole is a bridge between two distant regions of spacetime. In the classical theory of general relativity, nothing is allowed to pass through the wormhole. In 2019, Daniel Jafferis of Harvard University and his collaborators suggested that a wormhole might be traversable when created by entangled black holes. Kolchmeyer, a postdoc working with CTP and LNS Harlow researchers and assistant professor Netta Engelhardt, was advised by Jafferis for his PhD.

“These physicists discovered a quantum mechanism for making a wormhole traversable by introducing a direct interaction between distant regions of spacetime, using a simple quantum dynamic system of fermions,” says Kolchmeyer. “In our work, we also used these entangled quantum systems to produce this kind of ‘wormhole teleportation’ using quantum computing and were able to confirm the results with classical computers.”

Professor Maria Spiropulu and Jafferis of Caltech are the lead authors of the new study, which appeared on December 1 in Nature. Lead authors include Kolchmeyer and Zlokapa from MIT, as well as Joseph D. Lykken from the Fermilab Quantum Institute and Theoretical Physics Department, and Hartmut Neven from Google Quantum AI. Samantha I. Davis and Nikolai Lauk are other Caltech and Alliance for Quantum Technologies (AQT) researchers.

Remote spooky action

In this experiment, the researchers sent a signal “through the wormhole” by teleporting a quantum state from one quantum system to another on the 53-qubit Sycamore quantum processor. To do this, the research team needed to determine entangled quantum systems that behaved with the properties predicted by quantum gravity, but were also small enough to run on today’s quantum computers.

“A central challenge for this work was to find a fairly simple quantum many-body system that preserves gravitational properties,” says Zlokapa, a second-year physics graduate student at MIT who began this research as an undergraduate. cycle in the laboratory of Spiropulu.

To achieve this, the team used techniques from machine learning, taking highly interactive quantum systems and gradually reducing their connectivity. The result of this learning process produced many examples of systems with behavior compatible with quantum gravity, but each instance only required about 10 qubits – a perfect size for the Sycamore processor.

“The complex quantum circuits required would have made larger systems with hundreds of qubits impossible to run on the quantum platforms available today, so finding such small examples was important,” says Zlokapa.

Confirmed by classical computers

Once Zlokapa and the researchers identified these 10-qubit systems, the team inserted a qubit into one system, applied an energetic shockwave to the processor, and then observed that same information on the processor’s other quantum system. The team measured the amount of quantum information transmitted from one quantum system to another depending on the type of shock wave applied, negative or positive.

“We have shown that if the wormhole is held open long enough by the negative energy shockwaves, a causal path is established between the two quantum systems. The qubit inserted into one system is indeed the same one that appears on the other system,” Spiropulu explains.

The team then verified these and other properties with standard computer calculations. “It’s different from running a simulation on a conventional computer,” says Spiropulu. “Although one could simulate the system on a conventional computer – and it was done as shown in this article – no physical system is created in a conventional simulation, which is the manipulation of bits, zeros and ones Here we have seen the information travel through the wormhole.

This new work opens up the possibility of future quantum gravity experiments with larger quantum computers and more complex entangled systems. This work does not replace direct observations of quantum gravity, for example from gravitational wave detections using the Laser Interferometer Gravitational Wave Observatory (LIGO), adds Spiropulu.

Both Zlokapa and Kolchmeyer are keen to understand how such experiments can help advance quantum gravity. “I’m very curious to see how far we can probe quantum gravity on today’s quantum computers. We have concrete ideas for follow-up work that I’m excited about,” Zlokapa says.

This work is supported by a grant from the Office of High Energy Physics Department of Energy’s QuantISED program on “Quantum Communication Channels for Fundamental Physics”.

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