What problem does quantum cryptography solve?

- [Instructor] We are approaching the third decade of the 21st century. Earth is a hyper-connected world. Billions of people and devices are connected over global networks. Exabytes and data flows largely unhindered, near light speed across the planet. In the next few years, a few more billion people will join. Hundreds of billions of new devices will be connected, and a scale of data stored and transported will continue to rise quickly. This remarkable internet of people and things is powering a fourth industrial revolution that will eventually change so much of how we live, work, play. Innovation in this new revolution will have greater scope, impact, and velocity than at any time in our short human history. Alongside this hyper-connected world, we're now dealing with massive risks to our data and systems. All over the world, cyber criminals are active, and they're often successful in stealing data and identities, extorting ransoms, and exposing information. Nation states are using cyber as a new domain for cyber attacks and spying on adversaries. Fortunately, 100 billion dollar cyber security industry has emerged to counter these threats. Unfortunately, they play a cat and mouse game where for every defense that appears, the cyber criminals find a way around it. In the long run, the world needs radically new and effective innovation to protect our systems, data, and networks. That innovation is coming and will take many forms. For example, the promise of artificial intelligence is already helping to change the cyber security game for the better. Just like quantum mechanics promises to change our model for classical computing, and usher in a new generation of capability and performance, quantum mechanics may also offer a compelling set of solutions in the cyber security domain. We're still in the early days of research and development, but already, quantum networks and quantum cryptography are proving a tease at what may be possible. Without exaggeration, a fully realized quantum network may be impenetrable. That's game-changing, and so compelling that innovation in this space is moving rapidly forward. Quantum networks and cryptography use the unique properties of particles and waves to protect the data as it travels across the internet. For example, copying or observing data as it travels, changes the quantum state of information, thus notifying the sender recipient, or even making the data unusable. This makes a popular form of cyber theft impossible. Something called a man in the middle attack where a cyber criminal secretly relays and possibly alters the communications between the two points. Basic quantum cryptography is already possible, and I'll discuss it in a later video, but a full quantum network with robust quantum cryptography is still many years away. However, researchers are getting more confident with each experiment that they are trending in the right direction to realize the promise of a quantum secure future.