Entangled ever after

While religious ceremonies were the norm in the old days, today there are many ways to tie the knot. You can choose to have a conventional civil ceremony or, if you are feeling more adventurous, you can head to Vegas for an Elvis wedding. Themed weddings are in fact all the rage in the geek community, with star trek, stars wars or superheroes being common themes. Now, there is yet another way for science geeks to celebrate their special day: they can have a “quantum marriage.”

Until July 30, the AC Institute in New York City is offering the possibility of having a wedding officiated by quantum physics. Jonathan Keats, a self-called “experimental philosopher,” devised an apparatus that unites couples through quantum entanglement.

In the quantum sense, the word entanglement is used to describe two particles that remain connected (in that they can instantaneously communicate with one another), no matter how far apart they are. This means that they are linked in such a way that changes in a particle’s properties immediately change the properties of the other. The phenomenon is so odd that Einstein called it “spooky action at a distance.” But experiments have proved it to be real and quantum entanglement now has applications in areas such as quantum teleportation and quantum computing.

Simple experiments can be devised to create entangled photons (particles of light). When a photon passes through matter, an electron in the material absorbs the light particle and becomes more energetic. Eventually, the electron emits the photon by returning to its ground state, its lower level of energy. When the material is of a certain type, such as a crystal called beta-barium borate, the photon that the electron emits is more likely to split into two photons (with a combined energy equal to that of the original light particle). When this happens, the resulting photon pair is said to be entangled.

Given this connection, so strong that remains valid even when the particles are light-years apart, it is easy to understand why Keats decided to apply the concept of quantum entanglement to a romantic union. And because science knows how to produce entangled photons, the experimental philosopher felt couples could be united by being bombarded by these entangled particles of light through a simple experimental set-up. Keats explained how the process works in an email correspondence with Discovery News:

In the simplest case, involving only two people, the couple begins by walking down a long hallway from darkness into sunlight. (The hallway is wide enough for them to walk side by side, but too narrow to accommodate more than two people at a time.) At the end of the hallway, the couple will find two sets of footprints, on which they’ll stand facing one another, nearly touching. (Depending on their preference, they may be dressed or naked.) They’ll look up and see a window bright with sunlight, and suspended in that window above their heads they’ll find the entanglement apparatus, which has been precisely calibrated (using a system of adjustable prisms) to divide the sunlight passing through a nonlinear crystal (made of beta-barium borate) so that half of the light shines on each person’s face. They’ll stand for approximately a minute, allowing countless entangled photons to bombard their skin, gently entangling their flesh by the photoelectric effect. Then they’ll turn away and walk back down the hall and out into the open.

However, the couple will never be sure if the photons that bombarded them were indeed entangled. While a photon that passes through beta-barium borate is more likely to split in two than if it were to pass through a different material, it is not certain—-we are talking about a quantum phenomenon after all—-that such a photon will indeed be divided into two entangled ones.

Further, if we try to measure the properties of these particles, they instantly become disentangled. As explained on the AC Institute website, “Even those who get entangled will have to take their entanglement on faith, as any attempt to measure a quantum system disentangles it: A quantum marriage will literally be broken up by skepticism about it.”

There are other aspects that make this form of union different from a conventional marriage. You can, for example, be entangled to more than one person. According to the Nature News blog, “entanglement with non-humans is also feasible,” Keats said.

“Conventional weddings must meet church or state standards for couples to be married,” he added, “the nuptial entanglement process is totally open, as nondenominational and nonpartisan as the laws of physics.”


Keats explains how his apparatus works. Source: Science Friday.

To D&J and C&C, now (conventionally) married.


2 thoughts on “Entangled ever after

  1. Laura Wheeler

    I hope the couples that do go through this live "Happily ever entangled!" What a strange, sciency take on a wedding.
    For another take on those interested in marriage and statistics, have you heard of Wedding betting? It’s a high stake "game" where complete strangers can study profiles and pictures of newly married strangers and try their hand at predicting how long the marital bliss will last….


  2. Mike Fowler

    A very fine post, Barbara. You’ve finally allowed me to think I might understand something about quantum physics.
    Except, that means I probably don’t understand it, doesn’t it? Do I understand it worse now than when I thought I didn’t understand it? My thoughts are now hopelessly entangled. Anyway it’s nice to see Physicists borrowing a term from Biologists for once.


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