Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 58: Characterization and control of complex quantum systems SYQS 3 (with Q, MO, MS, MP, AGjDPG)

A 58.5: Invited Talk

Friday, March 21, 2014, 17:45–18:15, Audimax

Complexity and many-boson coherence — •Malte Tichy — Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus, Denmark

Many-boson systems feature a subtle interplay of complexity and coherence. Many-boson coherence is a source of complexity, which makes Boson-Sampling -- the simulation of many-boson interference -- a paradigm that may demonstrate the superiority of quantum devices. However, current protocols that aim at certifying the functionality of Boson-Sampling setups are shown to be bypassed by an efficient model with randomly prepared independent particles. An alternative test based on a solvable instance of the problem is shown to permit more stringent certification for arbitrarily many particles [1]. The protocol paves the road to rule out alternative models for many-particle behavior that extricate themselves from true complexity. Bosonic composites made of two constituents, however, deviate from ideal elementary bosonic behavior when their constituents are not sufficiently entangled. The complexity of the constituent wavefunction thus becomes a requirement for the ideal collective bosonic behavior of composites and the absence of complexity leads to observable deviations [2].

[1] Malte C. Tichy, Klaus Mayer, Andreas Buchleitner, Klaus Mølmer, arXiv:1312.3080 (2013). [2] Malte C. Tichy, P. Alexander Bouvrie, Klaus Mølmer, Phys. Rev. A 86, 042317 (2012); Phys. Rev. A 88, 061602(R) (2013).