title: Prospects for quantum computing with an array of ultracold polar paramagnetic molecules.
abstract: Arrays of trapped ultracold molecules represent a promising platform for implementing a universal quantum computer. DeMille [Phys. Rev. Lett. 88, 067901 (2002)] has detailed a prototype design based on Stark states of polar (1)Σ molecules as qubits. Herein, we consider an array of polar (2)Σ molecules which are, in addition, inherently paramagnetic and whose Hund's case (b) free-rotor pair-eigenstates are Bell states. We show that by subjecting the array to combinations of concurrent homogeneous and inhomogeneous electric and magnetic fields, the entanglement of the array's Stark and Zeeman states can be tuned and the qubit sites addressed. Two schemes for implementing an optically controlled CNOT gate are proposed and their feasibility discussed in the face of the broadening of spectral lines due to dipole-dipole coupling and the inhomogeneity of the electric and magnetic fields.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
authors.forename: Mallikarjun
authors.initials: M
authors.lastname: Karra
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
authors.forename: Ketan
authors.initials: K
authors.lastname: Sharma
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
authors.forename: Bretislav
authors.initials: B
authors.lastname: Friedrich
authors.affiliation: Departments of Chemistry, Physics and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Sabre
authors.initials: S
authors.lastname: Kais
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
authors.forename: Dudley
authors.initials: D
authors.lastname: Herschbach