# US 10,371,767 B2 · Efficient spin polarization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,371,767 B2 - Document ID: US10371767B2 - Status: Granted - Kind: B2 - Application number: 14/888,169 - Filed: 2014-01-31 - Published: 2016-03-10 - Granted: 2019-08-06 - Earliest claimed: 2013-05-03 - Assignees: Quantum Valley Investment Fund LP - Applicants: Quantum Valley Investment Fund LP - Inventors: Troy Borneman; David G. Cory; Christopher James Wood - Web page: https://patentgrep.com/patent/US10371767B2 ## CPC - G01R 33/282: {Means specially adapted for hyperpolarisation or for hyperpolarised contrast agents, e.g. for the generation of hyperpolarised gases using optical pumping cells, for storing hyperpolarised contrast agents or for the determination of the polarisation of a hyperpolarised contrast agent} - G01N 24/08: by using nuclear magnetic resonance (G01N24/12 takes precedence) - G01N 24/10: by using electron paramagnetic resonance (G01N24/12 takes precedence) - G01R 33/30: Sample handling arrangements, e.g. sample cells, spinning mechanisms - G01R 33/3804: {Additional hardware for cooling or heating of the magnet assembly, for housing a cooled or heated part of the magnet assembly or for temperature control of the magnet assembly} - G01R 33/3856: {Means for cooling the gradient coils or thermal shielding of the gradient coils} - G01R 33/44: using nuclear magnetic resonance [NMR] (G01R33/24, G01R33/62 take precedence) - G01R 33/50: based on the determination of relaxation times {, e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences} - G01R 33/56: Image enhancement or correction, e.g. subtraction or averaging techniques {, e.g. improvement of signal-to-noise ratio and resolution} - G01R 33/60: using electron paramagnetic resonance (G01R33/24, G01R33/62 take precedence) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract In some aspects, polarization of a spin ensemble can be increased using cavity-based techniques. A cavity is coupled with a spin ensemble, and a drive field generates an interaction between the cavity and the spin ensemble. In some cases, the interaction increases the polarization of the spin ensemble faster than the thermal (T1) relaxation process or any other thermal polarizing process affecting the spin ensemble. In some cases, polarization is increased by iteratively acting on angular momentum subspaces of the spin ensemble, and mixing the angular momentum subspaces, for example, by a dipolar interaction, a transverse (T2) relaxation process, application of a gradient field, or a combination of these and other processes. ## Claims ### Claim 1 A method of controlling a spin ensemble comprising: coupling a cavity mode of a cavity with spin states of the spin ensemble in a sample environment, the sample environment comprising a static magnetic field, the spin ensemble defining a state space comprising a plurality of angular momentum subspaces, wherein the angular momentum subspaces are defined by a total angular momentum spin operator for the spin ensemble; and generating an interaction between the cavity and the spin ensemble that increases polarization of the spin ensemble faster than the dominant thermal polarizing process affecting the spin ensemble in the sample environment, wherein the interaction is generated by the coupling between the spin states and the cavity mode acting independently on each of the plurality of angular momentum subspaces of the spin ensemble. ### Claim 2 (depends on 1) The method of claim 1, comprising increasing polarization of the spin ensemble by iteratively: acting on each of the plurality of angular momentum subspaces; and mixing the angular momentum subspaces. ### Claim 3 (depends on 2) The method of claim 2, where the angular momentum subspaces are mixed by at least one of a dipolar interaction, a transverse (T2) relaxation process, or application of a gradient field. ### Claim 4 (depends on 2) The method of claim 2, comprising controlling a temperature of the cavity by operation of a cooling system that is thermally coupled to the cavity. ### Claim 5 (depends on 1) The method of claim 1, wherein the interaction between the cavity and the spin ensemble cools the spin ensemble. ### Claim 6 (depends on 1) The method of claim 1, wherein the interaction between the cavity and the spin ensemble heats the spin ensemble. ### Claim 7 (depends on 1) The method of claim 1, wherein generating the interaction comprises applying a drive field to the spin ensemble, the drive field being adapted to couple the spin states of the spin ensemble with the cavity mode of the cavity. ### Claim 8 (depends on 7) The method of claim 7, wherein the drive field is tuned to a spin-resonance frequency (ωs) of the spin ensemble, the cavity mode corresponds to a cavity-resonance frequency (ωc), and the cavity-resonance frequency (ωc) is detuned from the spin-resonance frequency (ωs) by an amount δω=ωc−ωs. ### Claim 9 (depends on 1) The method of claim 1, wherein the dominant thermal polarizing process comprises thermal relaxation having a characteristic relaxation time T1, and the interaction between the cavity and the spin ensemble increases polarization of the spin ensemble at a polarization rate that is related to a parameter of the cavity and is faster than the characteristic relaxation time T1. ### Claim 10 A magnetic resonance system comprising: a cavity defining a cavity mode that couples with spin states of a spin ensemble in a static magnetic field, the spin ensemble defining a state space comprising a plurality of angular momentum subspaces, wherein the angular momentum subspaces are defined by a total angular momentum spin operator for the spin ensemble; and a resonator adapted to generate an interaction between the cavity and the spin ensemble that increases polarization of the spin ensemble faster than the dominant thermal polarizing process affecting the spin ensemble, wherein the interaction between the cavity and the spin ensemble is generated as a result of the coupling between the spin states and the cavity mode acting independently on each of the plurality of angular momentum subspaces. ### Claim 11 (depends on 10) The system of claim 10, wherein the resonator and the cavity are distinct structures. ### Claim 12 (depends on 10) The system of claim 10, comprising an integrated multi-mode resonator structure that includes the resonator and the cavity. ### Claim 13 (depends on 10) The system of claim 10, further comprising: a primary magnet system adapted to generate the static magnetic field; and a sample containing the spin ensemble. ### Claim 14 (depends on 10) The system of claim 10, further comprising a cooling system thermally coupled to the cavity and adapted to cool the cavity. ### Claim 15 (depends on 14) The system of claim 14, wherein the cooling system comprises at least one of a liquid nitrogen cryostat, a liquid helium cryostat, a closed-loop refrigerator, a pumped-helium cryostat, a helium-3 refrigerator, or a dilution refrigerator. ### Claim 16 (depends on 14) The system of claim 14, wherein the cooling system is thermally coupled to a sample containing the spin ensemble, and the cooling system is adapted to cool the sample.