Abstract
Much of the anticipation accompanying the development of a quantum computer relates to its application to simulating dynamics of another quantum system of interest. Here, we study the building blocks for simulating quantum spin systems with linear optics. We experimentally generate the eigenstates of the Hamiltonian under an external magnetic field. The implemented quantum circuit consists of two cnot gates, which are realized experimentally by harnessing entanglement from a photon source and applying a cphase gate. We tune the ratio of coupling constants and the magnetic field by changing local parameters. This implementation of the model using linear quantum optics might open the door to future studies of quenching dynamics using linear optics.
- Received 30 September 2014
DOI:https://doi.org/10.1103/PhysRevX.5.021010
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Published by the American Physical Society
Popular Summary
The idea of quantum simulations is attributed to Richard Feynman who first proposed using well-controllable quantum systems to simulate more complex systems, the properties of which cannot easily be computed using classical computers. In this way, an easily accessible system can be used for reproducing the behavior of complex quantum states. This insight of having one controllable quantum system simulate another is what forms the foundation of quantum simulations.
Here, we study the simulation of quantum spin systems under an external magnetic field using linear optics. We use entangled photon pairs and apply various variable single-qubit gates and a two-qubit gate to them. We are able to generate the eigenstates of the Hamiltonian for two spins, including the ground state. We study how these eigenstates behave when we change parameters corresponding to the magnetic field and the coupling between the spins. This generation of eigenstates could be the starting point for more complex quantum simulations such as studies of quenching dynamics.
We expect that our results will pave the way for more complex quantum simulations using photonic systems. The integrated manipulation of photons on a chip will provide stable environments that will make it possible to develop integrated quantum simulators.
