Entanglement
Two or more quantum particles such as qubits can be linked in perfect unison through entanglement.
These entangled particles remain perfectly connected, even if they are separated by great distances.
Two qubits are entangled by using a laser beam.
Once the qubits are linked, they are in an indeterminate state.
They can be separated by any distance, and still remain entangled. They are twins.
When you manipulate one of the qubits, the change also happens immediately to the other qubit.
Once you have entangled qubits, you can have great fun with them, such as using them for superdense coding, which can speed up processing for particular applications. Like warp drive for code.
You can also establish quantum teleportation, to exchange information between quantum computers and run their processes in parallel. The entangled qubit twins enable the computers to be twins.
And you can certainly explore quantum cryptography with entangled qubits. Quantum cryptography uses the power of quantum computers to form an unbreakable encryption, to protect data.
The encryption is unbreakable because of the laws of quantum physics. If anyone tried to intercept the signal, it would destroy the connection, which is based on a wave function.
A wave function is a mathematical concept, but it can represent complex physical systems.
In the laws of quantum mechanics, the act of observation has consequences. Observation affects the system, and the impact is that the wave function describing the system no longer applies: it collapses.
The system itself doesn’t collapse, but the wave function does. So when you are communicating securely on a quantum network, any attempted eavesdropping instantly interferes with the entangled qubits, and alerts all participants.
The eavesdropper is tied to the issue of the observer effect, where a measurement necessarily requires interacting with the physical object being measured, affecting its properties through the interaction.
So quantum cryptography uses quantum computers and is unbreakable. That is quantum computers being used for defense.
Quantum computers can also be used for offense, for hacking operations to break older encryption on classical computers.
No one knows when quantum computers will become powerful enough to hack current algorithms; estimates include: now, or in five years, or more than ten. But most experts agree it is a matter of when, not if.
So new algorithms are needed to run on current computers, which is called post quantum cryptography, or PQC. Post-quantum means the algorithms will survive the arrival of fully powerful quantum computers.
The reason these algorithms are needed now is because hackers are already stealing encrypted data when they break into networks, in SNDL attacks: store now, decrypt layer.
Quantum Cryptography = using quantum computers to encrypt data
Post-Quantum Cryptography = using new algorithms now to encrypt data that will survive quantum computers.
And this is all made possible by . . . entangled particles.
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