Quantum Lunch Location:
T-Division Conference Room, TA-3,
Building 123, Room 121
Quantum Institute: Visitor Schedule
The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.
To add your name to the Quantum Lunch email list, contact Charlotte Carter
Thursday, April 16, 2009
12:30 PM - 2:00 PM
Speaker: Tobias Schaetz, Max-Planck-Institut für Quantenoptik, Garching, Germany
Technical Host: John Chiaverini
TOPIC: What's up spins? Simulating quantum systems in ion traps
We study the building blocks for quantum simulations based on trapped ions. In the first part of the talk we focus on quantum spin-Hamiltonians simulated according to a protocol of Porras and Cirac (PRL 2004). Here, we experimentally simulated the adiabatic evolution of the smallest non-trivial spin system from para- into ferromagnetic order with a quantum magnetisation for two spins of 98%. We proved that the transition was not driven by thermal-fluctuations but of quantum mechanical origin, the source of quantum-fluctuations in quantum phase transitions. We observed a final superposition state of the two degenerate spin configurations for the ferromagnetic order corresponding to deterministic entanglement achieved with 88% fidelity. To calibrate the amplitudes of the simulated interactions, we performed a two-qubit phase-gate based on both axial motional modes with an entangling fidelity exceeding 95%. Currently, we explore the limits of quantum simulations in conventional traps, extending the operations to the radial degree of freedom, with a preliminary fidelity of the two-qubit phase-gate exceeding 97% and recently five ions cooled close to the motional ground state. In parallel we work on the realization of a surface-trap array that might allow for a 2D-lattice of ions (first of 2x2 – in principle scalable to >10x10 ions/spins). In a second part of the talk we want to present our experimental results of a quantum (random) walk of an ion – our protocol being close to the proposal of Travaglione and Milburn (PRA 2002).
In collaboration with A.Friedenauer, H.Schmitz, J.T.Glueckert, and D.Porras.