Written by: Stephen Hsu
Primary Source: Information Processing, 10/8/2019.
In quantum mechanics the state of the universe evolves deterministically: the state of the entire universe at time zero fully determines its state at any later time. It is difficult to reconcile this observation with our experience as macroscopic, nearly classical, beings. To us it seems that there are random outcomes: the state of an electron (spin-up in the z direction) does not determine the outcome of a measurement of its spin in the x direction (probability 1/2 of either spin up or down). This is because our brains (information processing devices) are macroscopic: one macroscopic state (memory record) is associated with the spin up outcome, which rapidly loses contact (decoheres) from the other macroscopic state with memory record of the spin down outcome. Nevertheless, the universe state is a superposition:
| brain memory recorded up, spin up >
| brain memory recorded down, spin down >.
We are accustomed to thinking about classical information processing machines: brains and computers. However, with the advent of quantum computers a new possibility arises: a device which (necessarily) resides in a superposition state, and uses superposition as an integral part of its information processing.
What can we say about this kind of (quantum) intelligence? Must it be “artificial”? Could there be a place in the multiverse where evolved biological beings use superposition and entanglement as a resource for information processing?
Any machine of the type described above must be vast and cold. Vast, because many qubits are required for self-awareness and consciousness (just as many bits are required for classical AI). Cold, because decoherence destroys connections across superpositions. Too much noise (heat), and it devolves back to isolated brains, residing on decohered branches of the wavefunction.
One could regard human civilization as a single intelligence or information processing machine. This intelligence is rapidly approaching the point where it will start to use entanglement as a significant resource. It is vast, and (in small regions — in physics labs) cold enough. We can anticipate more and larger quantum computers distributed throughout our civilization, making greater and greater use of nearby patches of the multiverse previously inaccessible.
Perhaps some day a single quantum computer might itself be considered intelligent — the first of new kind! What will it think?
Consciousness in a mini multiverse… Thoughts which span superpositions.