Squeezing and entanglement in multi-qutrit systems

We study squeezing and bipartite entanglement in a multi-qutrit system initially in a coherent state, initiated by the two-axis counter-twisting Hamiltonian in the presence and also absence of a magnetic field. We start with an initial coherent state which is neither squeezed nor entangled; however, it gains both properties as it is evolved by the Hamiltonian. Both squeezing and entanglement show an oscillatory behavior in time and stronger Hamiltonians correspond to smaller oscillation periods. Generation of almost continuous squeezing according to Kitagawa criterion seems feasible; however, off and on squeezing death is observed according to that of Wineland. The entanglement is diminished as the size of the system is increased, implying that the generation of strong entanglement in large multi-qutrit systems, instigated by the counter-twisting Hamiltonian, may not be feasible. Application of a magnetic field may have adverse effect on both squeezing and entanglement.

[1]  Wineland,et al.  Squeezed atomic states and projection noise in spectroscopy. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[2]  M. Jafarpour,et al.  Thermal Spin Squeezing as a Signature of Thermal Global Entanglement in Heisenberg Models , 2012 .

[3]  Barry C. Sanders,et al.  Spin squeezing and pairwise entanglement for symmetric multiqubit states , 2003 .

[4]  Xiaoguang Wang.  Spin squeezing in nonlinear spin-coherent states , 2001, quant-ph/0103061.

[5]  W. Wootters.  Entanglement of Formation of an Arbitrary State of Two Qubits , 1997, quant-ph/9709029.

[6]  Qutrit squeezing via semiclassical evolution , 2011, 1108.4717.

[7]  Spin squeezing and entanglement in spinor condensates , 2002, quant-ph/0203015.

[8]  Degree of entanglement for two qutrits in a pure state , 2003, quant-ph/0305043.

[9]  G. Vidal,et al.  Computable measure of entanglement , 2001, quant-ph/0102117.

[10]  Klaus Mølmer,et al.  Entanglement and extreme spin squeezing. , 2000, Physical review letters.

[11]  Ueda,et al.  Squeezed spin states. , 1993, Physical review. A, Atomic, molecular, and optical physics.

[12]  K. Mølmer,et al.  Pairwise entanglement in symmetric multi-qubit systems , 2001, quant-ph/0106145.

[13]  Moore,et al.  Spin squeezing and reduced quantum noise in spectroscopy. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[14]  A. Klyachko,et al.  Entanglement of qutrits , 2007 .

[15]  C. Caves,et al.  Concurrence-based entanglement measures for isotropic states , 2003 .

[16]  M. Jafarpour,et al.  Entanglement and squeezing of multi-qubit systems using a two-axis countertwisting Hamiltonian with an external field , 2008 .