37-Dimension Experiment Shows Quantum Physics is Even Stranger

The search for the most paradoxical quantum states of particles led physicists to create an unusual experiment.

Physicists have created particles of light that actually exist in 37 dimensions at once to test an extreme version of the quantum paradox.

The scientists say the experiment shows that quantum physics is much more different from classical physics than many thought. The study is published in the journal Science Advances, New Scientist reports.

The study’s authors focused on the Greenberger-Horne-Zeilinger (GHZ) paradox, which shows that quantum particles can remain linked over large distances.

In the simplest version of the paradox, three particles are linked by quantum entanglement, a special connection that allows observers to learn something about one particle by interacting with the other two.

As previous experiments have shown, the situation where particles can only influence each other when they are in close proximity, i.e. quantum entanglement is forbidden, leads to mathematical impossibilities.

In fact, the paradox can be expressed through a calculation that ends with 1 and -1 being equal, which cannot be true. In the 1990s, physicists realized that the only way to avoid such impossibilities is to accept that particles can participate in quantum entanglement.

The authors of the study wanted to create the most extreme version of this paradox to date. Specifically, they wanted to find states of photons, or particles of light, whose behavior in the GHZ experiment would be as different as possible from the behavior of particles in classical physics.

Calculations showed that photons must exist in quantum states as complex as if they existed in 37 dimensions. Just as your state right now can be defined using three spatial dimensions and one time dimension, defining the state of each photon requires 37 such dimensions.

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Physicists tested this idea by translating a multidimensional version of the GHZ paradox into a series of pulses of highly coherent light—that is, light that is extremely uniform in color and wavelength—that scientists could then control.

Physicists say that the state encoded by the light and its measurements are governed by the same mathematics that underlies quantum physics.

The experiment can therefore produce some of the most non-classical effects in the quantum world. This type of quantum simulation is extremely technically challenging and requires very stable and precisely calibrated devices.

The scientists say the results of the experiment could still be relevant 100 years from now. In addition to probing the limits of quantumness, the new work could also have implications for how quantum states of light and atoms are used to process information, such as in quantum computing.