title: Experimental creation of quantum Zeno subspaces by repeated multi-spin projections in diamond.
abstract: Repeated observations inhibit the coherent evolution of quantum states through the quantum Zeno effect. In multi-qubit systems this effect provides opportunities to control complex quantum states. Here, we experimentally demonstrate that repeatedly projecting joint observables of multiple spins creates quantum Zeno subspaces and simultaneously suppresses the dephasing caused by a quasi-static environment. We encode up to two logical qubits in these subspaces and show that the enhancement of the dephasing time with increasing number of projections follows a scaling law that is independent of the number of spins involved. These results provide experimental insight into the interplay between frequent multi-spin measurements and slowly varying noise and pave the way for tailoring the dynamics of multi-qubit systems through repeated projections.
authors.affiliation: QuTech, Delft University of Technology, P.O. Box 5046, Delft 2600 GA, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, Delft 2600 GA, The Netherlands.
authors.forename: N
authors.initials: N
authors.lastname: Kalb
authors.affiliation: QuTech, Delft University of Technology, P.O. Box 5046, Delft 2600 GA, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, Delft 2600 GA, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Cramer
authors.affiliation: Element Six Innovation, Fermi Avenue, Harwell Oxford, Didcot, Oxfordshire OX11 0QR, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Twitchen
authors.affiliation: Element Six Innovation, Fermi Avenue, Harwell Oxford, Didcot, Oxfordshire OX11 0QR, UK.
authors.forename: M
authors.initials: M
authors.lastname: Markham
authors.affiliation: QuTech, Delft University of Technology, P.O. Box 5046, Delft 2600 GA, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, Delft 2600 GA, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Hanson
authors.affiliation: QuTech, Delft University of Technology, P.O. Box 5046, Delft 2600 GA, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, Delft 2600 GA, The Netherlands.
authors.forename: T H
authors.initials: TH
authors.lastname: Taminiau