Abstract: The method can be applied to a quantum system having a non-linear element coupled to a resonator, the non-linear element having a quantum state changeable between a plurality of quantum states and the resonator having a resonance frequency. The method can include driving the resonator; the resonator resonating at a first frequency in response to said driving the resonator; and simultaneously to said driving the resonator, driving the non-linear element at the first frequency.

Abstract: Disclosed is a system (200) for autonomous stabilisation of quantum states, comprising: a quantum harmonic oscillator (202), an auxiliary device (201) dispersively coupled to the oscillator (202), a dissipater (203), an exciter (204) configured to generate first (205, 405) and second (206, 406) frequency combs, intended to be sent to at least one among the quantum harmonic oscillator (202), the auxiliary device (201) and dissipater (203) characterised in that a first frequency difference separating two successive lines of the first frequency comb (205, 405) is equal to twice a second frequency difference separating two successive lines of the second comb (206, 406).

Abstract: Control system (1) for a state of a quantum harmonic oscillator, comprising: —a harmonic oscillator (3) in a Schrödinger's cat type state, —a stabilisation device (10) with a predetermined parity of a number of bosons of the state, which device is configured to use first and second frequency combs each comprising at least as many rays as a mean number of bosons in the state, and —a multiphonic dissipation device (20) which is suitable for removing at least one pair of bosons simultaneously from the oscillator, the dissipation device being activated only between two successive time peaks of the frequency combs over a time period greater than the inverse of the product of the mean number and the inverse of the characteristic time of the multiphonic dissipation, a time period separating two activation periods being less than a characteristic loss time of a boson.

Abstract: Disclosed is a system (200) for autonomous stabilisation of quantum states, comprising: a quantum harmonic oscillator (202), an auxiliary device (201) dispersively coupled to the oscillator (202), a dissipater (203), an exciter (204) configured to generate first (205, 405) and second (206, 406) frequency combs, intended to be sent to at least one among the quantum harmonic oscillator (202), the auxiliary device (201) and dissipater (203) characterised in that a first frequency difference separating two successive lines of the first frequency comb (205, 405) is equal to twice a second frequency difference separating two successive lines of the second comb (206, 406).

Abstract: A joint timelapse full waveform inversion (FWI) method for estimating physical properties of a subsurface includes receiving seismic data related to the subsurface, wherein the seismic data includes a baseline dataset dB and a monitor dataset dM, defining an objective function of the FWI method, calculating a baseline gradient gB of the objective function for the baseline dataset dB, and a monitor gradient gM of the objective function for the monitor dataset dM, computing a baseline preconditioner P?B for the baseline dataset dB and a monitor preconditioner P?M for the monitor dataset dM so that each of the baseline preconditioner P?B and the monitor preconditioner P?M reflects similarities and/or differences of geometrical features of the baseline and monitor acquisition surveys, and determining physical properties of the subsurface based on a baseline physical properties update and a monitor physical properties update.

Abstract: A least-square migration, LSM, based method for generating a 4D image of a subsurface, the method including receiving seismic data d related to the subsurface, the seismic data d including a baseline dataset dB and a monitor dataset dM, calculating a baseline filter B and a monitor filter M based on a same common reflectivity r of the subsurface and corresponding remigrated baseline data mB1 and remigrated monitor data mM1 so that the base filter B applied to the remigrated baseline data mB1 equals the monitor filter M applied to the remigrated monitor data mM1, applying the baseline filter B to raw migrated baseline data mB0 and applying the monitor filter M to raw migrated monitor data mM0 to generate LSM baseline data mB and LSM monitor data mM, and generating the 4D image of the subsurface based on the LSM baseline data mB and the LSM monitor data mM.

Abstract: Control system (1) for a state of a quantum harmonic oscillator, comprising:—a harmonic oscillator (3) in a Schrodinger's cat type state,—a stabilisation device (10) with a predetermined parity of a number of bosons of the state, which device is configured to use first and second frequency combs each comprising at least as many rays as a mean number of bosons in the state, and—a multiphonic dissipation device (20) which is suitable for removing at least one pair of bosons simultaneously from the oscillator, the dissipation device being activated only between two successive time peaks of the frequency combs over a time period greater than the inverse of the product of the mean number and the inverse of the characteristic time of the multiphonic dissipation, a time period separating two activation periods being less than a characteristic loss time of a boson.