The Fatal Flaw

Mission 0: The Information Problem. Part of the Quantum Courier Service, a free course from the Oxford University Quantum Information Society.

The Fatal Flaw: The Ghost in the Wires

If the classical bit is so elegant, why are we losing the war? Because classical information has the loyalty of a highly gossipy butler. It will gladly repeat your deepest, darkest secrets to absolutely anyone who asks, without a single blush. It is completely indifferent to being watched.

The Classical Spy's Playbook: The Shameless Exhibitionism of Classical Bits

In our everyday macroscopic world, observation is entirely passive. If you read a rare, forbidden manuscript in the Duke Humfrey's Library, the ink doesn't evaporate just because your eyes scanned it.

The exact same thing happens in our cables. When Agent Alice wants to send a "1", she sends a 5-volt pulse of electricity down the wire. To intercept this, the Echo Network doesn't cut the cable. They just clamp a voltmeter onto our wire and siphon off a completely negligible fraction of a volt, just enough to read the data. The remaining 4.99 volts cruise merrily along to Agent Bob, who receives the perfect "1" and goes to make a cup of tea, entirely oblivious to the fact that his operational security has just been comprehensively ruined.