200 likes | 434 Views
Adiabatic quantum computer (AQC). Andrii Rudavskyi Supervisor: p rof. Petra Rudolf . Outline…. Adiabatic quantum algorithm Problems which can be solved How to make AQC work? Qubit, couplers, detectors Examples of real device. Adiabatic quantum algorithm. Initialize ground state
E N D
Adiabatic quantumcomputer (AQC) Andrii Rudavskyi Supervisor: prof. Petra Rudolf
Outline… • Adiabatic quantum algorithm • Problems which can be solved • How to make AQC work? Qubit, couplers, detectors • Examples of real device
Adiabatic quantum algorithm • Initialize ground state • Slowly alter Hamiltonian • Read solution encoded in final Hamiltonian ground state
NP-complete − problems which cannot be solved within polynomial time: Factorization of integers Search in unsorted databases Travelling salesman problem Image recognition Artificial intelligence What kind of problems can be solved?
CUBO-Quadratic unconstrainedbinary optimization , where • NP-hard • Ising model; describes real physical systems • Use quantum physics to solve math
Qubit − quantum unit which encodes the state Coupler − device which couples qubits Device which measures the result of computation What do we need to construct AQC? Couplers Qubits
What kind of hardware to use? Superconductors: • Semiconductor planar technology is highly developed and can be implemented in superconductors • Generate almost no heat • Superconductor logic is very fast
Superconducting flux qubit • Superconducting current and magnetic field created by it cannot be arbitrary. They are quantized • Single wave function • Analogy with Bohr atomic orbits
Superconducting flux qubit • Superconducting current and magnetic field created by it cannot be arbitrary. They are quantized • Single wave function • Analogy with Bohr atomic orbits • We cannot change magnetic flux through the loop
Dielectric Superconducting flux qubit
Separate superconductors have different phase. φ – phase difference • Current through the junction • Energy of the junction I Dielectric Superconductor Josephson junction
Josephson persistent-current qubit • Calculate Josephson energy of the loop • Two stable minima of energy correspond to opposite currents Science 285, 1037 (1999)
Coupling • Coupling via inducting coil • SQUID controls strength of coupling
Two-Qubit system • FM coupling • Non coupling • AFM coupling
Conclutions: • AQC − good alternative to conventional quantum computer • All logical elements are easily built with help of well developed lithographic planar technology • 28-qubit AQC is already built and 1000 is not far off
Thank you for attention!