Quantum simulations of a qubit of space
In loop quantum gravity approach to Planck scale physics, quantum geometry is
represented by superposition of the so-called spin network states. In the
recent literature, a class of spin networks promising from the perspective of
quantum simulations of quantum gravitational systems has been studied. In this
case, the spin network states are represented by graphs with four-valent nodes,
and two dimensional intertwiner Hilbert spaces (qubits of space) attached to
them. In this article, construction of quantum circuits for a general
intertwiner qubit is presented. The obtained circuits are simulated on 5-qubit
(Yorktown) and 15-qubit (Melbourne) IBM superconducting quantum computers,
giving satisfactory fidelities. The circuits provide building blocks for
quantum simulations of complex spin networks in the future. Furthermore, a
class of maximally entangled states of spin networks is introduced. As an
example of application, attempts to determine transition amplitudes for a
monopole and a dipole spin networks with the use of superconducting quantum
processor are made.
Grzegorz Czelusta Jakub Mielczarek