Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 16: Poster: Quantum information, micromechanical oscillators, matter wave optics, precision measurements and metrology

Q 16.2: Poster

Montag, 17. März 2014, 16:30–18:30, Spree-Palais

Efficient Optimization of Quantum Gates for Rydberg Atoms and Transmon Qubits under Dissipative Evolution — •Michael H. Goerz, Daniel M. Reich, and Christiane P. Koch — Universität Kassel, Institut für Theoretische Physik

We consider two different physical systems to illustrate an efficient optimization of quantum gates under dissipative evolution, requiring the propagation of only three states, irrespective of the dimension of the Hilbert space. In the first example, two trapped neutral atoms are excited to a Rydberg state, via a decaying intermediary state. The interaction between both atoms in the | rr ⟩ state allows for the realization of a diagonal CPHASE gate. Optimal control theory finds a solution that uses a STIRAP-like mechanism to suppress population in the decaying intermediary state, while implementing the desired gate. As a second example, we consider two superconducting transmon qubits coupled via a shared transmission line resonator. The Hamiltonian in this case also allows for non-diagonal gates, and we optimize for a √iSWAP, taking into account energy relaxation and dephasing of the qubits. The system is driven at a frequency close to the center between both qubits, and the optimized gate exploits a near-resonance of the | 0 ⟩ → | 1 ⟩ transition on the left qubit and the | 1 ⟩ → | 2 ⟩ transition on the right qubit. For both examples, the gate fidelity reached by optimization is only limited by the decoherence.