Three physicists, Alain Aspect, John Clauser, and Anton Zeilinger, have won the 2022 Nobel Prize in Physics for demonstrating the potential to investigate and control particles in entangled states through experiments. Their combined investigations have shown the existence of entanglement, a quantum phenomenon in which two particles communicate even if they are too far apart to affect each other.
The research “For experiments with entangled photons, establishing the violations of Bell inequalities and pioneering quantum information science” has created the groundwork for a new age of quantum technology.
Entanglement was at the core of a debate in the 1930s between Albert Einstein, Niels Bohr, and Erwin Schrödingerl. Einstein felt that all components of reality should be tangible and entirely understandable. However, Bohr, Schrödinger, and other pioneers of emerging quantum mechanics discovered that fact appeared to be inherently indeterminate; a particle does not possess particular attributes until it is measured. The physicist John Bell devised a decisive thought experiment, which Alain Aspect and John Clauser eventually implemented in many experimental forms.
Dr Clauser used duct tape and spare parts to measure quantum entanglement in 1972 by firing hundreds of photons in opposing directions to explore a feature known as polarization. When he measured the polarizations of photon pairs, he discovered a correlation, demonstrating that a concept known as Bell’s inequality, a theory developed by John Bell, had been broken and that the photon pairs were entangled. The research affirmed Schrödinger’s claim. Quantum mechanics was the universe’s operating system.
“Being able to manipulate and manage quantum states and all their layers of properties gives us access to tools with unexpected potential,”
the Nobel Prize committee
To understand quantum entanglement, consider two electrons. When measured, they display a behaviour called spin. It means they can take one of two values: “up” or “down.” Measuring the spin of each electron is like throwing a coin: it will come out up or down at random.
When Alain measures a spin-up electron, John’s matching half of the electron pair is spin-down, and vice versa. The two acts of measurement are linked, almost as if flipping one coin might send out a signal that instantly secures the correct outcome of its other half at the time of measurement.
The applications are vast.
The upshot of the research was seminal for Quantum Information theory which is driving a range of industries, from Quantum Computing, where qubits are used in place of classical bits, but also in security, where the properties of entanglement can be used to create secure communication systems.