 Close your eyes and picture the deepest darkest secrets Now imagine if everybody found out about it This is not that hard to believe That's already happened to one in four Australians who have had some form of their personal information compromised This mystery man in black here is the one who exposed your secrets He could be anyone from your friendly neighborhood hacker to powerful organization So trying to steal your information through their constant coordinated efforts But how do they get their hands on your secrets? Can't you keep your secrets safe with encryption? Encryption works by taking your information and scrambling it using a key So that only people with that key can unscramble and access your information But this key is not perfectly safe If someone has a fast enough computer, they can eventually crack it through trial and error and you'd never know Like this girl in the picture We are unaware and therefore powerless to stop them from invading our privacy But I can use quantum physics to make sure you know if someone is looking at your data Let's say you want to share a secret with someone I Can write your secret into single particles of light called photons a Fundamental quantum property of these photons is that you can't look at them without changing them You can use this to test if someone is snooping on you before you even send out your secret message The good news is we can already send messages using these photons The bad news is we can only send these photons over short distances because of how fragile they are To keep these photons safe over long distances. We can set up relay stations along the way At these relays we need to catch and hold on to these photons until the relay is ready Catching these particles of lights is exactly what I'm working on I Can use lasers to cool down atoms to 40,000 times colder than outer space. I Can use these atoms to slow down lights to about the speed of a car This lets me catch and hold on to these photons Once the relay is ready, I can release these photons back to the speed of light towards the next relay Once I can catch and store these photons reliably your information will become perfectly secure There will be no one Aside from you who can reveal the deepest darkest secrets Thank you