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Quantifying Superposition
Johan Aberg
Measures are introduced to quantify the degree of superposition in mixed states with respect to orthogonal decompositions of the Hilbert space of a quantum system. These superposit…
Non-Abelian generalization of off-diagonal geometric phases
David Kult, Johan Åberg, Erik Sjöqvist
If a quantum system evolves in a noncyclic fashion the corresponding geometric phase or holonomy may not be fully defined. Off-diagonal geometric phases have been developed to deal…
Operational approach to the Uhlmann holonomy
Johan Aberg, David Kult, Erik Sjöqvist +1
We suggest a physical interpretation of the Uhlmann amplitude of a density operator. Given this interpretation we propose an operational approach to obtain the Uhlmann condition fo…
Manifestations of quantum holonomy in interferometry
Erik Sjöqvist, David Kult, Johan Åberg
Abelian and non-Abelian geometric phases, known as quantum holonomies, have attracted considerable attention in the past. Here, we show that it is possible to associate nonequivale…
Fidelity and Coherence Measures from Interference
Daniel K. L. Oi, Johan Aberg
By utilizing single particle interferometry, the fidelity or coherence of a pair of quantum states is identified with their capacity for interference. We consider processes acting…