Quantum Communications – Part 1

 Computers, communications, photonics, cybersecurity…… some of my favorite technologies all bundled together in quantum communications! But… what is it? How does it work? Let's take an introductory look.

In quantum mechanics, something called superposition allows systems to exist in multiple states simultaneously - like a spinning coin being both heads and tails at once, until observed. Only measurement forces it into a definite state. This principle affects quantum information through the no-cloning theorem, which states that it's impossible to create an exact copy of an unknown quantum state due to quantum mechanics' mathematical foundations. This feature enables quantum key distribution (QKD), which creates unbreakable encryption keys. Any eavesdropping attempt disturbs the quantum states due to the no-cloning theorem, instantly revealing the intrusion. While classical information can be copied perfectly, quantum information's resistance to copying both protects it and makes quantum teleportation the only way to transfer quantum states.

 

How about an example? Let’s now compare sending a classical letter and sending a quantum letter using two diagrams I’ve created. These diagrams split into two parallel workflows showing classical versus quantum communication highlight the key security advantages of quantum communication over classical methods.

 

The classical letter path shows a letter that can be intercepted, read, and copied without detection as it moves from sender to recipient through the postal system.

The quantum letter path illustrates how quantum letters behave differently:

• The letter exists in superposition (blue state) until measured
• Any attempt to read/copy disturbs the quantum state (changes to red)
• This disturbance is detectable when received by the recipient, revealing tampering

We’ll dig a little deeper in future posts – for now think of quantum communication as the first step toward a quantum internet - one that operates on the powerful principles of quantum physics rather than classical physics. While we may not see quantum email on our phones anytime soon, the technology is steadily advancing from science fiction toward practical reality.