Resonance states in atomic and quantum dot models

FEDERICO M. PONT; OMAR OSENDA; JULIO H. TOLOZA; PABLO SERRA

Sao Carlos

Taller; Spin 2010 - 1st Sao Paulo School of Advanced Science: Spintronics and Quantum Computation; 2010

In quantum few-body systems a resonance state is a localized metastablestate. The main difference with bound states is that they have a finite life-time after which the system delocalizes. In this work we studied resonancestates of a one-electron atomic model and two-electron quantum dot (QD).Both systems were studied using complex scaling techniques and variationalexpansions with real-basis functions. In the real-basis approach, we estimatedthe resonance Energy and Lifetime using the density of states(DOS) fromknown stabilization methods. For the one-electron model we improved thestabilization method in order to obtain numerical convergence with increasingbasis-set size. The resonance energy for the two-electron QD was calculatedusing DOS and a Fidelity based quantity. Thinking towards a possible use ofresonances in QD for quantum computation, we proposed a definition of thevon Neumann entropy (an entanglement witness) for a resonance state. Theentropy was calculated using real-basis sets and complex-scaled quantities.Both techniques showed excellent agreement for the real part of the entropy.