Stopping the rot

Philip C. E. Stamp

Uncontrollable outside influences undermine the whole enterprise of quantum computing. Nailing down the sources of this 'decoherence' in a solid-state system is a step towards solving the problem.

Rick P. Trebino

L.D. Faddeev, L.A. Khalfin, I.V. Komarov

We propose to treat Maxwell equations as a wave equation of motion for a photon (a quantum of light) and to develop the photon mechanics on this basis. Consider vectors of electric and magnetic fields E and H as a single object (a bivector) F , which corresponds to the function ψ in the wave theory of the electron. Multiplying the vacuum Maxwell equations − rotH+ 1 c ∂E ∂t = 0, rot E + 1 c ∂H ∂t = 0 (1) by hc 2πi , it is possible to rewrite them in the form HF + h 2πi ∂F ∂t = 0, (2) where H is the operator H = hc 2πi { 0 − rot rot 0 } ; (3) its meaning follows from the comparison of equation (2) with (1). Equation (2) can be interpreted as a wave equation for a photon.

Alexei S. Trifonov

Chatterjee, Rohit, Xiao Rong Liang, Omkant Pandey

We close the gap between black-box and non-black-box constructions of composable secure multiparty computation in the plain model under the minimal assumption of semi-honest oblivious transfer. The notion of protocol composition we target is angel-based security, or more precisely, security with super-polynomial helpers. In this notion, both the simulator and the adversary are given access to an oracle called an angel that can perform some predefined super-polynomial time task. Angel-based security maintains the attractive properties of the universal composition framework while providing meaningful security guarantees in complex environments without having to trust anyone. Angel-based security can be achieved using non-black-box constructions in max(R_OT,Õ(log n)) rounds where R_OT is the round-complexity of semi-honest oblivious transfer. However, current best known black-box constructions under the same assumption require max(R_OT,Õ(log² n)) rounds. If R_OT is a constant, the gap between non-black-box and black-box constructions can be a multiplicative factor log n. We close this gap by presenting a max(R_OT,Õ(log n)) round black-box construction. We achieve this result by constructing constant-round 1-1 CCA-secure commitments assuming only black-box access to one-way functions.

Merle Colby, David A. Katcher