For the first time, researchers at MIT, Caltech, Harvard University and elsewhere sent quantum information through a quantum system in what could be thought of as going through a wormhole. Although this experiment did not create a disruption of physical space and time in the way we might understand the term “wormhole” from science fiction, calculations from the experiment showed that the qubits traveled from one system of entangled particles to another in a gravity model. . This experiment performed on Google’s Sycamore quantum processor device opens the door to future experiments with quantum computers to investigate ideas from string theory and gravitational physics.
“Simulating strongly 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 and researcher at MIT. Laboratory of Nuclear Science (LNS) that works with David Kolchemeyer, one of the main authors of the work. “This is a promising initial step.”
In a new paper in Nature, a team of physicists, including MIT’s 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 hole worm traversing
A wormhole is a bridge between two remote space-time regions. In the classical general theory of relativity, nothing can pass through the wormhole. In 2019, Daniel Jafferis of Harvard University and his collaborators suggested that a wormhole could be traversed when created by entangled black holes. Kolchmeyer, a postdoctoral fellow working with CTP and LNS researchers Harlow and assistant professor Netta Engelhardt, was advised by Jafferis for his Ph.D.
“These physicists discovered a quantum mechanism to make a wormhole traversable by introducing a direct interaction between distant regions of spacetime, using a simple quantum dynamical 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.”
Caltech professor Maria Spiropulu and Jafferis are lead authors of the new study, which appeared Dec. 1 in Nature. Lead authors include Kolchmeyer and Zlokapa of MIT, as well as Joseph D. Lykken of the Fermilab Quantum Institute and Department of Theoretical Physics, and Hartmut Neven of Google Quantum AI. Other Caltech and Alliance for Quantum Technologies (AQT) researchers on the paper include Samantha I. Davis and Nikolai Lauk.
Spooky action at a distance
In this experiment, the researchers sent a signal “through the wormhole” teleporting a quantum state from one quantum system to another in 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 work with today’s quantum computers.
“A central challenge for this work was finding a simple enough quantum many-body system that preserves gravitational properties,” says Zlokapa, a second-year physics student at MIT who began this research as an undergraduate in the lab of Spiropulu.
To achieve this, the team used machine learning techniques, taking highly interactive quantum systems and gradually reducing their connectivity. The output of this learning process produced many examples of systems with behavior consistent with quantum gravity, but each instance required only 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 quantum platforms available today, so it was important to find such small examples,” says Zlokapa.
Confirmed by classic computers
Once Zlokapa and the researchers identified these 10-qubit systems, the team inserted a qubit into one system, applied a shock wave of energy to the processor, and then observed that same information in the other quantum system in the processor The team measured how much quantum information passed from one quantum system to the other depending on the type of shock wave applied, negative or positive.
“We showed that if the wormhole is opened long enough by the negative energy shock waves, a causal path is established between the two quantum systems. The qubit embedded in a system is actually the same one that appears in the other system,” says Spiropulu.
The team then verified these and other properties with classical computer calculations. “This is different from running a simulation on a classic computer,” says Spiropulu. “Although the system could be simulated on a classical computer, and this was done as reported in this paper, no physical system is created in a conventional simulation, which is the manipulation of classical bits, zeros, and ones . Here we saw information traveling through the wormhole.”
This new work opens up the possibility of future quantum gravity experiments with larger quantum computers and more complicated entangled systems. This work does not replace direct observations of quantum gravity, for example from detections of gravitational waves using the Laser Interferometer Gravitational-Wave Observatory (LIGO), Spiropulu adds.
Both Zlokapa and Kolchmeyer are interested in understanding how these experiments can help advance quantum gravity. “I’m very curious to see how far we can investigate quantum gravity on today’s quantum computers. We have some concrete ideas for follow-up work that I’m very excited about,” says Zlokapa.
This work is supported by a grant from the Energy Office of High Energy Physics’ QuantISED program on “Quantum communication channels for fundamental physics”.
/University Study. This material from the original organization/author(s) may be ad hoc in nature, edited for clarity, style and length. The views and opinions expressed are those of the author(s). See them in full here.