## Cosmic Correction Code

The smallest memory units in quantum computers are extremely prone to errors - which can, however, be compensated for with the help of complicated circuits. Now theoretical physicists are speculating that similar quantum corrections could stabilize spacetime.

In 1994 everyone was suddenly talking about quantum computers. The US mathematician Peter Shor had just shown how the devices can, in principle, crack modern cryptographic processes by breaking down large numbers into their factors very quickly. Quantum computers were purely hypothetical at the time, and one fundamental problem stood in the way of their construction: the sensitivity of the physical components.

In contrast to the binary bits in ordinary computers, these "qubits" consist of quantum objects. Its value is not fixed, but only the probabilities of encountering a qubit in one of the states |0〉 or |1〉 can be specified up to the point of measurement. In addition, the still uncertain states of two qubits can couple to each other, making them "entangled". Then the possible states of each qubit depend on those of all others. With each arithmetic operation, the available contingent of different probabilities increases. The number of all these simultaneous settings is growing exponentially. If they can be obtained and manipulated, quantum computing will become enormously powerful - at least in theory…