Researchers have demonstrated one of the perplexing features of quantum mechanics at a much larger scale. Their study could open doors for potentially revolutionary technologies like quantum computers and new kinds of sensors.
For decades, scientists have tried to prove that one of the most peculiar properties of quantum mechanics isn’t just a mathematical quirk, but a real feature of the physical world. The phenomenon, which Albert Einstein called ‘spooky action at a distance’, also known as ‘quantum entanglement’, refers to systems that can’t be described independently of each other, regardless of how far apart they are.
Entanglement has already been demonstrated for microscopic-scale systems involving photons, ions, electron spins, and microwave and electromechanical devices. But a team of researchers partially supported by the EU-funded project HOT has shown that entanglement could also be generated and detected on a larger scale. The study is crucial because entanglement is considered a key resource for a number of potentially transformative quantum technologies, including quantum computation and information transmission.
Their findings were recently published in the journal ‘Nature’. As they explain, their study “qualitatively extends the range of entangled physical systems and has implications for quantum information processing, precision measurements and tests of the limits of quantum mechanics.”
According to a news release by Aalto University in Finland, researchers via laboratory measurements managed to bring two distinct and moving objects – nearly visible to the naked eye – into an entangled quantum state where they feel each other. It added: “The objects in the experiments were two vibrating drumheads fabricated from metallic aluminium on a silicon chip. The drumheads are truly massive and macroscopic compared to the atomic scale: their diameter is similar to the width of a thin human hair.”
Quoted in the same release, Prof. Mika Sillanpää of Aalto University’s Department of Applied Physics and team leader, said: “The vibrating bodies are made to interact via a superconducting microwave circuit. The electromagnetic fields in the circuit carry away any thermal disturbances, leaving behind only the quantum mechanical vibrations.”
The team eliminated all forms of environmental disturbances, so they conducted the experiment at temperatures close to absolute zero, at – 273 °C. The researchers found that their approach led to states of entanglement which lasted for long periods of time, sometimes up to half an hour. They say that the study paves the way for more precise manipulation of the properties of macroscale objects. This could eventually be put to use to make new kinds of routers and sensors.
Teleportation, but not in the science fiction sense
The team also hopes to use quantum teleportation to transmit the vibrations between the two drumheads. Dr Caspar Ockeloen-Korppi, one of the team members quoted in the release, said “we are still pretty far from Star Trek though.”
Summarising the study in the British edition of ‘The Conversation’, Dr Matt Woolley, one of the researchers, said that the experiment “is perhaps the closest approach to a literal implementation of the famous thought experiment of Einstein, Podolsky and Rosen that first studied the phenomenon that became known as entanglement back in 1935.” Einstein had devised a paradox meant to show that quantum theory was incomplete, as explained in a joint article with Boris Podolsky and Nathan Rosen, which was published in the journal ‘Physical Review’.
The ongoing HOT (Hybrid Optomechanical Technologies) project focuses on nano-optomechanical devices comprising electrical, microwave or optical systems with micro- and nano-mechanical systems.