Science, Technology, and Society Studies

Interaction-assisted SU(2) adiabatic holonomies in Josephson phase qubits

“…( 10), we require good control over B, which is not a problem experimentally. In a typical experiment, even for long times, the magnetic field (the microwave drive) can easily be controlled [11].…”

Maximally entangling tripartite protocols for Josephson phase qubits

“…For example, the GHZ state can be generated by e −iα |GHZ = e −i(π/2)σ 2 z e −i(π/3)(σ 1 y −σ 2 y ) U int e −i(π/12)(5σ 1 y +σ 2 y −3σ 3 y ) e −i(π/2)σ 2 z |000 , with α = −π/2, t GHZ = (2/3) × (π/2g). To generate the W state, we generalize Neeley's fast implementation for triangular g(XX + Y Y ) coupling [23] (cf. [24]) to arbitrary coupling g(XX +Y Y )+ gZZ, including the Heisenberg exchange g = g: e −iα |W = e +i(π/3)σ 2 z U int e −i(π/2)σ 2 y |000 , with α = (5g − 2g) π/18g, t W = (4/9) × (π/2g).…”

Greenberger-Horne-Zeilinger state protocols for fully connected qubit networks

“…[The term "delta" comes from the three-qubit case, where the system looks like a triangle, a special case of the "star-delta" or "Y-delta" transform in electrical engineering [21].] It is then straightforward to show that N qubits coupled to an island with capacitance C ⋆ are equivalent to N qubits coupled to each other in a complete graph with capacitance C ∆ = C ⋆ /N [20]. Thus, from the practical point of view, implementing a fully connected network using a solid state quantum computing architecture is relatively straightforward.…”

“…There is a nice experimental realization of fully connected networks involving capacitively coupled superconducting qubits proposed by Matthew Neeley and his collaborators at UCSB [20]. It consists of a superconducting island (an isolated piece of aluminum) connected via a capacitor to each of the qubits in the system.…”

“…(Color online) Optimal values of the final rotation angles α i opt , i = 1, 2, 3, and the entangling time topt that minimize the error due to coupling imperfections in the N = 3 case. The gate fidelity is defined in Eq (20)…”