Abstract We consider a system of two indistinguishable fermions (with four accessible states each) that suffers decoherence without dissipation due to its coupling with a global bosonic bath at a fixed temperature. Using an appropriate measure of fermionic entanglement, we identify families of two-fermion states whose entanglement persists throughout the evolution, either fully or partially, despite the noisy effects of the interaction with the bath, and independently of its temperature. The identified resilience to decoherence provides valuable insights into the entanglement dynamics of open systems of indistinguishable fermions, and into the conditions under which long-lived entanglement emerges under more general decoherence channels.
Abstract We consider a system of two indistinguishable fermions (with four accessible states each) that suffers decoherence without dissipation due to its coupling with a global bosonic bath at a fixed temperature. Using an appropriate measure of fermionic entanglement, we identify families of two-fermion states whose entanglement persists throughout the evolution, either fully or partially, despite the noisy effects of the interaction with the bath, and independently of its temperature. The identified resilience to decoherence provides valuable insights into the entanglement dynamics of open systems of indistinguishable fermions, and into the conditions under which long-lived entanglement emerges under more general decoherence channels.
Abstract We analyze the dynamics of entanglement due to decoherence in a system of two identical fermions with spin 3/2 interacting with a global bosonic environment. We make use of an appropriate measure of the so-called fermionic entanglement to quantify the fermionic correlations, and compare the dynamical effects due to decoherence with those that arise in a pair of distinguishable qubits immersed in the same environment. According to the system’s initial state, three types of qualitatively different dynamics are identified: i) invariant regime , corresponding to initial states that belong to a decoherence free subspace (DFS), which maintain invariant their entanglement and coherence throughout the evolution; ii) exponential decay , corresponding to initial states orthogonal to the DFS, and evolve towards states whose entanglement and coherence decrease exponentially; iii) entanglement sudden death , corresponding to initial states that have some overlap with the DFS and exhibit a richer dynamics leading, in particular, to the sudden death of the fermionic entanglement, while the coherence decays exponentially. Our analysis offers insights into the dynamics of entanglement in open systems of identical particles and into the existence of decoherence free subspaces and entanglement sudden death in indistinguishable-fermion systems.
We analyze the dynamics of entanglement due to decoherence in asystem of two identical fermions with spin 3/2 interacting with a global bosonicenvironment. We make use of an appropriate measure of the so-called fermionicentanglement to quantify the fermionic correlations, and compare the dynamicaleffects due to decoherence with those that arise in a pair of distinguishablequbits immersed in the same environment. According to the system?s initialstate, three types of qualitatively different dynamics are identified: i) invariantregime, corresponding to initial states that belong to a decoherence free subspace(DFS), which maintain invariant their entanglement and coherence throughoutthe evolution; ii) exponential decay, corresponding to initial states orthogonal tothe DFS, and evolve towards states whose entanglement and coherence decreaseexponentially; iii) entanglement sudden death, corresponding to initial states that havesome overlap with the DFS and exhibit a richer dynamics leading, in particular,to the sudden death of the fermionic entanglement, while the coherence decaysexponentially. Our analysis offers insights into the dynamics of entanglementin open systems of identical particles and into the existence of decoherence freesubspaces and entanglement sudden death in indistinguishable-fermion systems.
Coupling to a thermal bath leads to decoherence of stored quantum information. For a system of Gaussian fermions, the fermionic analog of linear or Gaussian optics, these dynamics can be elegantly and efficiently described by evolution of the system's covariance matrix. Taking both system and bath to be Gaussian fermionic, we observe that decoherence occurs at a rate that is independent of the bath temperature. Furthermore, we also consider a weak coupling regime where the dynamics are Markovian. We present a microscopic derivation of Markovian master equations entirely in the language of covariance matrices, where temperature independence remains manifest. This is radically different from behaviour seen in other scenarios, such as when fermions interact with a bosonic bath. Our analysis applies to many Majorana fermion systems that have been heralded as very robust, topologically protected, qubits. In these systems, it has been claimed that thermal decoherence can be exponentially suppressed by reducing temperature, but we find Gaussian decoherence cannot be cooled away.
Coupling to a thermal bath leads to decoherence of stored quantum information. For a system of Gaussian fermions, the fermionic analog of linear or Gaussian optics, these dynamics can be elegantly and efficiently described by evolution of the system's covariance matrix. Taking both system and bath to be Gaussian fermionic, we observe that decoherence occurs at a rate that is independent of the bath temperature. Furthermore, we also consider a weak coupling regime where the dynamics are Markovian. We present a microscopic derivation of Markovian master equations entirely in the language of covariance matrices, where temperature independence remains manifest. This is radically different from behaviour seen in other scenarios, such as when fermions interact with a bosonic bath. Our analysis applies to many Majorana fermion systems that have been heralded as very robust, topologically protected, qubits. In these systems, it has been claimed that thermal decoherence can be exponentially suppressed by reducing temperature, but we find Gaussian decoherence cannot be cooled away.
Information that is stored in quantum-mechanical systems can be easily lost because of the interaction with the environment in a process known as decoherence. Possible physical implementations of many processes in quantum information theory involve systems of identical particles, whence comprehension of the dynamics of entanglement induced by decoherence processes in identical-particle open systems becomes relevant. Here we study the effects and concomitant entanglement evolution arising from the interaction between a system of two identical fermions and the environment for two paradigmatic quantum channels. Entanglement measures are introduced to quantify the entanglement between the different parties, and a study of the dynamics of entanglement for some particular examples is carried out. Our analysis, which includes also the evolution of an entanglement indicator based on an entropic criteria, offers insights into the dynamics of entanglement in open systems of identical particles, involving the emergence of multipartite genuine entanglement. The results improve our understanding of the phenomenon of decoherence and will provide strategies to control it.
We use numerically exact iterative path integral methods to investigate the decoherence and entanglement dynamics of a tunneling pair of two coupled qubits (spins) system interacting with a dissipative bath. We find that decoherence is generally accompanied by the destruction of entanglement, although the specifics of this destruction depend sensitively on the parameters of the Hamiltonian (qubit-qubit coupling and/or energy bias), the strength of dissipation, the temperature, and the choice of initial condition. We also observe that dissipation can in some cases generate a substantial amount of entanglement. Finally, if an entangled eigenstate exists which does not couple to the environment, the long-time entanglement can significantly exceed the value corresponding to the Boltzmann equilibrium state.