Among other things, an apparatus comprises quantum units; and couplers among the quantum units. Each coupler is configured to couple a pair of quantum units according to a quantum Hamiltonian characterization of the quantum by the coupler.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. An apparatus comprising: quantum units; and couplers among the quantum units, each coupler being configured to couple a pair of quantum units such that a quantum Hamiltonian characterizing the quantum units and the couplers is: H tot = I  ( t )  ∑ i N   σ i x + G  ( t )  ( ∑ m ∈ { x , y , z }   ∑ i N   ɛ i , m  σ i m + ∑ m , n ∈ { x , y , z }   ∑ i < j N  g ijmn  σ i m  σ j n ) + P  ( t )  ( - ∑ i N  h i  σ i z + ∑ i N  J ij  σ i z  σ j z ) where εi,m denotes disorders and gijmn defines general two-body interaction parameters, N is the total number of pairs of quantum units, i represents the ith pair of quantum unit, hi and Jij have real values that are associated with coupling strength between the quantum units of each pair of quantum units, and I(t), G(t), and P(t) are time-dependent control parameters. 2. The apparatus of claim 1, wherein the quantum units comprises a first pair of superconducting quantum units, the first pair comprising: a first superconducting quantum unit configured to have controllable quantum operators σ1i, where i=x, y, or z and represents a direction in Hilbert space; a second superconducting quantum unit configured to have controllable quantum operators σ2i, where i=x, y, or z and represents a direction in the Hilbert space; and wherein the couplers comprise: a first coupler between the first and second superconducting units, wherein when a magnetic field is applied along the z direction, the first coupler couples the first superconducting unit with the second superconducting unit in a first coupling represented by σ1zσ2z; and a second coupler between the first and second superconducting units, wherein when the magnetic field along the z direction is applied, the second coupler couples the first superconducting unit with the second superconducting unit in a second coupling represented by σ1xσ2z+σ2xσ1z. 3. The apparatus of claim 2, wherein the first superconducting quantum unit comprises a first superconducting qubit and the controllable quantum operators ail are binary, and the second superconducting quantum unit comprises a second superconducting qubit and the controllable quantum operators σ2i are binary. 4. The apparatus of claim 2, wherein the first coupler and the second coupler comprise inductive couplers. 5. The apparatus of claim 2, wherein the couplers comprise a third coupler between the first and second superconducting units, wherein when the magnetic field along the z direction is applied, the second coupler couples the first superconducting unit with the second superconducting unit in a third coupling represented by σ1xσ2x. 6. The apparatus of claim 2, wherein each pair superconducting quantum units has the same structure as the first pair of superconducting quantum unit recited in claim 2, wherein different pairs of superconducting quantum units are coupled through additional couplers. 7. A method comprising: for a controllable quantum processor having controllable quantum states characterized by a quantum Hamiltonian Htotal, the quantum processor being controlled such that the Hamiltonian Htotal evolves from an initial quantum Hamiltonian Hi over time to a problem quantum Hamiltonian Hp, where an energy spectrum of Hp encodes a solution to a machine learning optimization problem, and where a quantum state of the quantum processor evolves from a ground state of Hi towards a ground state of Hp as Htotal evolves from H to Hp, deriving, by one or more processors, data characterizing a spontaneous energy spectrum of Htotal of the quantum processor, the deriving being based on a combination of Hi and Hp at a time that Htotal has the spontaneous energy spectrum; estimating based on, reorganization energy and frequency of the bath, by the one or more processors, an average phonon energy of a bath in which the piece of quantum hardware is located; and determining, by the one or more processors, an additional quantum Hamiltonian HQG based on the derived data characterizing the energy spectrum of Htotal and the calculated average phonon energy, such that when combined with Htotal, HQG limits evolution of the quantum state into the ground state of Hp as Htotal evolves to Hp without diagonalizing Hp. 8. The method of claim 7, comprising recording a selected probability mass function for the probability of the quantum state being in the ground state of Hp when Htotal evolves to Hp, and HQG is determined also based on the selected probability mass function and using the selected probability mass function in determining the additional quantum Hamiltonian. 9. The method of claim 7, wherein the spontaneous energy spectrum is obtained at approximately half time of a total time for Htotal to evolve from Hi to Hp. 10. The method of claim 7, wherein deriving the information about an energy spectrum of Htotal at the time of the quantum phase transition comprises evaluating ground state energy of Htotal using quantum Monte-Carlo techniques, mean-field theories, or Markus theory. 11. The method of claim 7, wherein the information about an energy spectrum comprises actual energy levels, spacing among the actual energy levels, distribution of the spacing among the actual energy levels, or an average spacing between adjacent average energy levels. 12. The method of claim 7, wherein calculating the average phonon energy of the bath comprises calculating the average phonon energy using an open quantum systems model. 13. The method of claim 12, wherein the average phonon energy satisfies the following equation: ω _ = ∑ 0 ∞  ω   J  ( ω )  d   ω / (  ω / kT - 1 ) ∑ 0 ∞  J  ( ω )  d   ω / (  ω / kT - 1 ) , where J(ω) is one of an Omhic spectral density: J  ( ω ) = λω    - ω γ , a super-Omhic spectral density: J  ( ω ) = λω  3   - ω γ , a Drude-Lorentz spectral density: J  ( ω ) = 2  λωγ ω 2 + γ 2 , and a flat spectral distribution: J(ω)=1, λ is a reorganization energy, and γ is a bath frequency cut-off. 14. The method of claim 7, wherein determining an additional quantum Hamiltonian HQG comprises selecting an exponential family of random matrices to represent a distribution of HQG and determining control parameters for the selected exponential family of random matrices. 15. The method of claim 7, wherein determining an additional quantum Hamiltonian HQG comprises determining HQG such that during the evolution of the Hamiltonian Htotal and the time the Hamiltonian Htotal has the spontaneous energy spectrum, excitations of the quantum state from a ground state of Htotal to an excited state of Htotal is suppressed, and after the time, the quantum state relaxes from an excited state of Htotal to the ground state of Htotal. 16. The method of claim 15, wherein HQG is determined such that, before the time, an average spacing Δg between energy levels of HQG and an average spacing Δε between energy levels of Htotal in combination are much larger than an average phonon energy Δω of the bath, and after the time, the average spacing Δg between the energy levels of HQG and the average spacing Δε between energy levels of Htotal in combination are similar to the average phonon energy Δε of the bath. 17. A method comprising: for a quantum processor solving a machine learning optimization problem, (a) encoding, by one or more processors, the machine learning optimization problem into an energy spectrum of a quantum Hamiltonian Htotal that characterizes the quantum processor, wherein the quantum processor is controllable such that Htotal evolves from an initial quantum Hamiltonian Hi over time to a problem quantum Hamiltonian Hp, wherein an energy spectrum of Hp encodes a solution to the machine learning optimization problem, and wherein a quantum state evolves from a ground state of H towards a ground state of Hp as Htotal evolves from Hi to Hp; (b) outputting a first set of control parameters based on the encoding for programming the quantum processor and parameterize Htotal; (c) deriving, by the one or more processors, an additional quantum Hamiltonian HQG, such that when combined with Htotal, HQG limits evolution of the quantum state into the ground state of Hp as Htotal evolves to Hp without diagonalizing Hp; (d) outputting a second set of control parameters based on the derived HQG for programming the quantum processor to reflect the parameterized Htotal; and (e) receiving, by the one or more processors from the quantum processor, output associated with a state of the quantum state at the end of the evolution. 18. The method of claim 17, comprising repeating steps (c)-(d) for a predetermined number of times, and performing a statistical analysis on the received outputs. 19. An apparatus comprising: quantum units; and couplers among the quantum units, each coupler being configured to couple a pair of quantum units, wherein the quantum units and the couplers are configured to be characterized by a quantum annealer and a quantum governor, and wherein the quantum units and the couplers are configured such that the quantum governor suppresses excitations of the quantum annealer from an instantaneous ground state to a higher energy state during a first period of time in a quantum annealing process, and facilitates relaxation of the quantum annealer from higher energy states to lower energy states or the ground state during a second period of time in the quantum annealing process. 20. The apparatus of claim 19, wherein the quantum annealer experiences four phases in the quantum annealing process, including initialization, excitation, relaxation, and freezing. 21. The apparatus of claim 20, wherein the first period of time comprises the initialization and excitation phases. 22. The apparatus of claim 21, wherein the second period of time comprises the relaxation and freezing phases. 23. The apparatus of claim 22, wherein in the first period of time, the quantum governor creates a mismatch between average phonon energy of a bath in which the quantum units and the couplers are located and an average energy level spacing of the quantum annealer to suppress unwanted excitations. 24. The apparatus of claim 22, wherein in the second period of time, the quantum governor enhances thermal fluctuations by creating an overlap between spectral densities of the quantum annealer and a bath in which the quantum units and the couplers are located.