Jan 4 2021
Researchers have reported successful quantum teleportation over a distance of around 27 miles. The achievement could be a significant step forward in the development of a quantum internet.
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A team of researchers from Fermilab and several partner institutes have reported the successful teleportation of qubits over a distance of 44 km. In a paper published in the journal PRX Quantum, the researchers describe for the first time a ‘sustained long-distance teleportation’ with a high data fidelity of 90 percent.
The qubits — basic units of information used in quantum computing and the equivalent of ‘bits’ in traditional computing — were teleported across a fiber-optic network and then detected with state-of-the-art photon-detectors and more common ‘off-the-shelf’ equipment.
“We’re thrilled by these results. This is a key achievement on the way to building a technology that will redefine how we conduct global communication.”
Panagiotis Spentzouris, Co-Author and Head of Quantum Science Program, Fermilab
Whilst the use of the word teleportation may bring to mind images from pop-culture of the crew of the Enterprise ‘beaming’ between alien vistas on the long-running sci-fi show Star Trek, quantum teleportation is actually somewhat different.
Rather than involving the movement of matter from one place-to-another, quantum teleportation actually describes the transmission of the state of a quantum system. This state essentially describes the qualities of a particular system — in this case, qubits — and thus, quantum teleportation really represents the transmission of information.
At the heart of quantum teleportation is an aspect of quantum physics that troubled its grandfather, Albert Einstein, so-deeply he labeled it “Spukhafte Fernwirkungen” or “spooky action at a distance.”
Ghost in the Machine: ‘Spooky Action at a Distance’ forms the Basis of Quantum Teleportation
Entanglement describes the connection between two or more particles that means a change in one causes an instantaneous and complementary change in the other. The aspect of this that Einstein found so troubling is that this change would occur instantaneously no matter how far apart the entangled particles are.
As an example of this, imagine two particles that are entangled so that when one is measured and takes the value ‘spin up’ — with ‘spin’ being a magnetic property of particles — the other will instantaneously become ‘spin down.’ These values are not adopted until a measurement is made, and once one takes a value, the other adopts a corresponding state — even if they are at opposite sides of the Universe.
This is comparable to teleportation as particles are identical, apart from the states they exist in. Thus forcing one particle to take the state of another is effectively the same as transporting the original particle from one location to another.
The great physicist felt that this violates the ‘Universal speed limit’ set by light traveling in a vacuum as the information is transferred instantly. Yet, despite these reservations, entanglement has proved its counter-intuitive nature time and time again, including in this record-setting study.
For quantum computing, this means the instant transfer of information across vast distances from one encoded system to its entangled partner and, eventually, even the possible development of a quantum internet comprised of linked quantum computers. But, there are limitations to this system that impedes its effectiveness.
Entangled systems can be quite sensitive and vulnerable to disturbance from environmental conditions. This delicacy has resulted in difficulty in teleporting qubits across great distances with accuracy. The 90% fidelity described by the Fermilab group indicates that the team has managed to eliminate much of this environmental noise.
Building a True Quantum Network
The team of researchers — which also included scientists from AT&T, Caltech, Harvard University, NASA Jet Propulsion Laboratory, and the University of Calgary — used two systems to teleport their qubits.
The Caltech Quantum Network (CQNET) and the Fermilab Quantum Network (FQNET) were designed, built, commissioned and deployed by Caltech’s public-private research program on Intelligent Quantum Networks and Technologies (IN-Q-NET) and feature near-autonomous data processing. This makes them compatible with existing telecommunications systems and with emerging quantum platforms for processing and storage.
“We are very proud to have achieved this milestone on sustainable, high-performing and scalable quantum teleportation systems. The results will be further improved with system upgrades we are expecting to complete by Q2 2021.”
Maria Spiropulu, Professor of Physics and Director of IN-Q-NET research program, California Institute of Technology
In July 2020, the U.S. Department of energy foreshadowed this research with the announcement of a blueprint for a quantum internet system that will cover the Chicagoland region. Alongside Argonne National Laboratory, Caltech, and Northwestern University, Fermilab — based in the area — has been integral in the design of this network — labeled the Illinois Express Quantum Network.
“The feat is a testament to the success of collaboration across disciplines and institutions, which drives so much of what we accomplish in science. I commend the IN-Q-NET team and our partners in academia and industry on this first-of-its-kind achievement in quantum teleportation.”
Joe Lykken, Deputy Director of Research, Fermilab
Thus, the team’s high fidelity teleportation of information over a distance of 44km could herald new opportunities in powerful computation, unparalleled precision sensing capabilities, and distributed secure communications.