Quantum Physics to Protect Votes

  • By Ari Daniel
  • Posted 11.10.16
  • NOVA

Voters want to be assured that every election is fraud-proof and hack-free. With the help of quantum mechanics, it’s possible to do just that — encrypt and transmit a vote in ways that can’t be tampered with.

Running Time: 05:23


Ari: The election’s upon us. And no matter whom you’re voting for, you likely want things to be fair. Free of fraud. No hacking.

So what if I told you there could be a way—two ways, actually—to ensure your vote is incredibly secure? Locked up and beyond tampering with, all thanks to the laws governing subatomic particles.

Ghose: Quantum mechanics offers completely radical, new, bizarre ways to implement security.

Ari: Using photons and electrons to protect your vote. Crazy? Maybe. But let’s face it—it might not be the craziest thing about this election.

First, let’s consider how messages you send electronically—like an email or a text, or a vote you cast online—get encrypted normally. You, as the sender, have a device that agrees on a secret code with the recipient’s device. This is also known as a key.

Ghose: For example, numbers correspond to the location of the letter in the alphabet. So you send a sequence of numbers, so that only the person who has the key can decrypt the encryption.

Ari: Since both you and your friend have the same key, when your encrypted message shows up on your friend’s device, it uses that key to unlock your original message. Now, this particular code—numbers swapped out for letters—is easy to crack. So we use computers and math to make more complicated codes—elaborate strings of 0’s and 1’s. But even the best codes get reverse engineered and hacked, sometimes without leaving a trace.

Ok, so I promised you two ways to achieve total security for your vote. Here’s way number one. And believe it or not, this is actually possible to do today. You generate a bunch of quantum particles…

Ghose: For example, photons, which are particles of light.

Ari: …and you control some property of each photon—their polarization, say, which is the direction the light’s electric field is oscillating in. And you convert that into zeros and ones.

Ghose: Vertical polarization is let’s say zero, and horizontal is one. For many, many photons, you have a whole sequence.

Ari: That sequence contains your key, your code—a string of zeros and ones that’s impossible to predict. You send your string to the polling station. A device on the other end measures the polarization of each of the incoming photons, and extracts the key based on your initial settings. That key can now be used to encrypt your vote and the polling station uses it to decode your vote. And here’s the best part. Let’s say some hacker tries to intercept the key. The simple act of observing a photon can disturb its polarization. That’s just quantum mechanics.

Ghose: If the sender and the receiver compare a few of their polarized photons and find that they don’t quite match, they can figure out that somebody else has been trying to read the information.

Ari: So the hacker can’t help but leave evidence of their meddling behind, and the key, now compromised, can be chucked and re-generated. The eavesdropper loses. Every time.

Ghose: The eavesdropper can never get around it because it’s built into the laws of physics. This is the only known cryptographic protocol that is perfectly secure.

Ari: The Swiss actually tried this successfully in their national election in 2007, in addition to traditional paper ballots.

Onto way number two to safeguard your vote. Entanglement. And I don’t mean political entanglement. I mean what happens when two particles—two photons, say—become tightly locked together. Whatever property one of them has, the other has too. Or they have the exact opposite. Always.

Ghose: They’re linked in a very powerful way, meaning whatever you do to one of the particles actually impacts the other particle instantly no matter where it is in the universe.

Ari: So let’s say you’ve got a bunch of particles in your home, each entangled with a corresponding particle at the polling station.

Ghose: That’s sort of like having an open channel between you and the polling station.

Ari: You cast your vote at home and it’s converted into a series of photons, each of them a zero or one just like before. You release these photons one at a time, and each of them meets an entangled photon in your home and interacts with it. Dances with it. And due to entanglement, the corresponding photon all the way at the polling station dances too. Which can be observed and used to reconstruct your original vote. Communicating between two entangled particles like this is the basis of quantum teleportation. And there’s no way to interfere with it.

Ghose: If anybody’s trying to steal your data or a vote or anything like this, instead of physically transmitting, there’s nothing to steal because it’s being teleported.

Ari: There are no wires, and no physical ballots. Just two particles tethered together in a way that’s impossible to hack.

So that’s how you create a tamper-free election. And learn something about the quantum world at the same time. A world that’s bizarre at every scale—from electron to election.



Production, Scripting, and Narration
Ari Daniel
Production Assistance
Janet DeFilippo
Special Thanks
Anne Barleon
Daryl Choa
City of Somerville, MA
© WGBH Educational Foundation 2016


Additional Visuals
Greg Kestin


(main image: spray of photons)
© WGBH Educational Foundation 2016

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