Abstract: A method for quantum metrology using stable non-equilibrium states of quantum matter, such as many-body quantum spin systems, is disclosed. The approach can utilize quantum correlations in such many-body quantum spin systems stabilized by strong interactions and periodic driving for reduction of noise. As an example, an exemplary protocol to perform Floquet enhanced measurements of an oscillating magnetic field in Ising-interacting spin systems is provided. These approaches allow for circumvention of the interaction-induced decoherence associated with high density spin ensembles and is robust to the presence of noise and imperfections. The protocol is applicable to nanoscale magnetic sensing and other precision measurements.

Abstract: According to some embodiments, a method for quantum metrology using these stable non-equilibrium states of quantum matter, such as many-body quantum spin systems, is disclosed. The approach can utilize quantum correlations in such many-body quantum spin systems stabilized by strong interactions and periodic driving for reduction of noise. As an example, disclosed is an exemplary protocol to perform Floquet enhanced measurements of an oscillating magnetic field in Ising-interacting spin systems. The approaches described herein allow for circumvention of the interaction-induced decoherence associated with high density spin ensembles and is robust to the presence of noise and imperfections. The protocol is applicable to nanoscale magnetic sensing and other precision measurements.

Abstract: A system comprising a solid state lattice containing an electronic spin coupled to a nuclear spin; an optical excitation configuration which is arranged to generate first optical radiation to excite the electronic spin to emit output optical radiation without decoupling the electronic and nuclear spins; wherein the optical excitation configuration is further arranged to generate second optical radiation of higher power than the first optical radiation to decouple the electronic spin from the nuclear spin thereby increasing coherence time of the nuclear spin; a first pulse source configured to generate radio frequency (RF) excitation pulse sequences to manipulate the nuclear spin and to dynamically decouple the nuclear spin from one or more spin impurities in the solid state lattice so as to further increase the coherence time of the nuclear spin; a second pulse source configured to generate microwave excitation pulse sequences to manipulate the electronic spin causing a change in intensity of the output optic

Abstract: A system comprising a solid state lattice containing an electronic spin coupled to a nuclear spin; an optical excitation configuration which is arranged to generate first optical radiation to excite the electronic spin to emit output optical radiation without decoupling the electronic and nuclear spins; wherein the optical excitation configuration is further arranged to generate second optical radiation of higher power than the first optical radiation to decouple the electronic spin from the nuclear spin thereby increasing coherence time of the nuclear spin; a first pulse source configured to generate radio frequency (RF) excitation pulse sequences to manipulate the nuclear spin and to dynamically decouple the nuclear spin from one or more spin impurities in the solid state lattice so as to further increase the coherence time of the nuclear spin; a second pulse source configured to generate microwave excitation pulse sequences to manipulate the electronic spin causing a change in intensity of the output optic

Abstract: A quantum ticket is defined by a unique serial number; and a set of qubits, each qubit encoding quantum information. The serial number and the set of qubits are distributed only among one or more trusted verifiers who require a tolerance fidelity Ftol in order to authenticate the token, where Ftol represents a minimum percentage of correct outcomes during authentication of the serial number and the set of qubits. The experimental fidelity Fexp for the quantum token is greater than the Ft0i set by the verifiers, so that an honest user of the quantum ticket who achieves Fexp is exponentially likely to be successfully authenticated when seeking authentication by any of the trusted verifiers. The forging fidelity Fforg for the quantum token is less than Ft0i, so that a dishonest user who achieves Fforg and attempts forgery of the quantum ticket is exponentially likely to fail to obtain authentication for his forged ticket.