A universal quantum computer may be emulated by a classical computing system that uses an electronic signal of bounded duration and amplitude to represent an arbitrary initial quantum state. The initial quantum state may be specified by inputs provided to the system and may be encoded in the signal, which is derived from a collection of phase-coherent coherent basis signals. Unitary quantum computing gate operations, including logical operations on qubits or operations that change the phase of a qubit, may be performed using analog electronic circuits within the quantum computing emulation device. These circuits, which may apply a matrix transformation to the signals representing the initial quantum state, may include four-quadrant multipliers, operational amplifiers, and analog filters. A measurement component within the quantum computing emulation device may produce a digital signal output representing the transformed quantum state. The gate operation(s) performed may be selected from among multiple supported operations.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A quantum computer emulation device, comprising: a basis state generator including circuitry to: receive a baseline signal; derive a plurality of phase-coherent signals from the baseline signal, wherein each of two or more pairs of signals in the plurality of phase-coherent signals is to represent a real component and an imaginary component of a signal for a single qubit; and multiply components of the single-qubit signals together to create a plurality of basis state signals; an initial quantum state generator including circuitry to: receive a plurality of direct current (DC) voltages, the DC voltages to represent complex coefficients; and generate, from the plurality of basis state signals and dependent on the plurality of DC voltages, a synthesized complex signal to represent a particular initial quantum state of two or more qubits; a first gate component including circuitry to: receive the synthesized complex signal; and perform a given operation on the synthesized complex signal to produce a modified complex signal, the modified complex signal to represent a transformed quantum state; and a measurement component including circuitry to: receive the modified complex signal; and output a digital signal, the digital signal to represent the transformed quantum state as measured. 2. The quantum computer emulation device of claim 1, wherein: the plurality of phase-coherent signals comprises two pairs of signals; the plurality of basis state signals comprises four basis state signals; and the synthesized complex signal is to represent the initial quantum state of two qubits. 3. The quantum computer emulation device of claim 1, wherein the initial quantum state generator further includes circuitry to: multiply each of the plurality of basis state AC signals by a respective pair of DC voltages, the pair of DC voltages to represent one of the complex coefficients; and add results of the multiplication of the basis state AC signals by the respective pairs of DC voltages to generate the synthesized complex signal. 4. The quantum computer emulation device of claim 1, wherein: the initial quantum state generator further includes circuitry to encode information to represent the initial quantum state in the frequency information in the synthesized complex signal; to produce the modified complex signal, the first gate component further includes circuitry to perform a matrix transformation on the synthesized complex signal; and the matrix transformation causes information to represent the transformed quantum state to be encoded in the frequency information in the modified complex signal. 5. The quantum computer emulation device of claim 1, wherein: to produce the modified complex signal, the first gate component is programmable to perform one of two or more supported quantum computing operations at a time, including the given operation; and to perform each of the two or more supported quantum computing operations, the first gate component further includes analog circuitry to perform one or more of: a multiplication operation; a summation operation; and a filtering operation. 6. The quantum computer emulation device of claim 1, wherein the quantum computer emulation device further comprises a second gate component including circuitry to: receive the modified complex signal; and perform a particular operation on the modified complex signal to produce a further modified complex signal, the further modified complex signal to represent a furthered transformed quantum state. 7. The quantum computer emulation device of claim 1, wherein: to produce the modified complex signal, the first gate component further includes circuitry to perform two or more supported quantum computing operations, including the given operation; at least one of the supported quantum computing operations is to operate on a single qubit; and at least one of the supported quantum computing operations is to operate on two or more qubits. 8. The quantum computer emulation device of claim 1, wherein to produce the modified complex signal, the first gate component further includes circuitry to: determine on which one or more of the qubits represented in the synthesized complex signal the given operation is to be performed; filter the synthesized complex signal to extract components of the synthesized complex signal that represent the one or more qubits on which the given operation is to be performed; and perform the given operation. 9. The quantum computer emulation device of claim 1, wherein: the quantum computer emulation device further comprises: a storage component; and circuitry to: direct the modified complex signal from an output of the first gate component to the storage component; and direct the modified complex signal from the storage component to an input of the first gate component; the first gate component further comprises circuitry to: receive the modified complex signal from the storage component; and perform a particular operation on the modified complex signal to produce a further modified complex signal, the further modified complex signal to represent a furthered transformed quantum state. 10. A method for emulating a quantum computer, comprising: generating a first pair of phase-coherent signals representing an initial quantum state of one or more qubits, the signals corresponding to real and imaginary parts of a complex signal, respectively; providing the first pair of signals as inputs to a first gate component that has been programmed to perform a given quantum computing operation; performing, by analog electronic circuits within the first gate component, the given quantum computing operation on the first pair of signals to produce a second pair of signals, the second pair of signals representing a transformed quantum state of at least one of the one or more qubits; providing an output of the first gate component to a measurement component; and producing, by the measurement component, a digital representation of the output of the first gate component. 11. The method of claim 10, wherein the first pair of phase-coherent signals represents an initial quantum state of two or more qubits. 12. The method of claim 10, wherein: the method further comprises, prior to providing an output of the first gate component to the measurement component: storing a representation of the second pair of signals for use in a subsequent quantum computing operation; providing the representation of the second pair of signals as inputs to the first gate component; and performing, by analog electronic circuits within the first gate component, the subsequent quantum computing operation on the second pair of signals to produce a third pair of signals, the third pair of signals representing a transformed quantum state of at least one of the one or more qubits; and providing an output of the first gate component to the measurement component comprises providing the third pair of signals to the measurement component. 13. The method of claim 10, further comprising, prior to providing the first pair of signals as inputs to the first gate component: programming the first gate component to perform the given quantum computing operation, including: providing, to the first gate component, inputs that cause the first gate component to perform a particular one of two or more quantum computing operations that are executable by the analog electronic circuits within the first gate component, the particular quantum computing operation including one or more of: a multiplication operation; a summation operation; and a filtering operation. 14. The method of claim 10, further comprising, prior to providing the first pair of signals as inputs to the first gate component: receiving a baseline signal; deriving a plurality of phase-coherent signals from the baseline signal, wherein each of two or more pairs of signals in the plurality of phase-coherent signals represents a real component and an imaginary component of a signal for a single qubit; multiplying components of the single-qubit signals together to create a plurality of basis state signals; receiving input representing a plurality of complex coefficients; and generating, from the plurality of basis state signals and dependent on the plurality of complex coefficients, the first pair of signals. 15. The method of claim 10, further comprising, prior to providing an output of the first gate component to the measurement component: performing, by analog electronic circuits of a second gate component within the first gate component, a second quantum computing operation on the second pair of signals to produce a third pair of signals, the third pair of signals representing a transformed quantum state of at least one of the one or more qubits; and providing an output of the first gate component to the measurement component comprises providing the third pair of signals to the measurement component. 16. A non-transitory computer readable medium storing instructions that when executed by a processor cause the processor to perform: receiving input defining an initial quantum state of one or more qubits to be encoded in a pair of phase-coherent signals, the signals representing real and imaginary parts of a complex signal, respectively; providing the input defining the initial quantum state to a quantum computing emulation device as one or more direct current (DC) values; receiving input defining a first quantum computing operation to be performed on the pair of signals into which the initial quantum state is encoded; providing the input defining the first quantum computing operation to the quantum computing emulation device as one or more pairs of DC values, each representing a complex coefficient of a matrix transformation to be applied by the quantum computing emulation device to transform the initial quantum state; receiving, subsequent to the performance of the first quantum computing operation on the pair of signals by the quantum computing emulation device quantum, a digital signal representing a modified quantum state as transformed by the quantum computing emulation device. 17. The non-transitory computer readable medium of claim 16, wherein when executed by the processor the instructions further cause the processor to perform: receiving input defining a plurality of basis states from which the pair of phase-coherent signals are to be derived; and providing the input defining the plurality of basis state to the quantum computing emulation device. 18. The non-transitory computer readable medium of claim 16, wherein receiving the input defining the first quantum computing operation comprises receiving input selecting one of a plurality of quantum computing operations supported in the quantum computing emulation device. 19. The non-transitory computer readable medium of claim 16, wherein: receiving the input defining the first quantum computing operation comprises receiving input specifying on which one or more of the one or more qubits the first quantum computing operation is to be performed; and the digital signal representing the modified quantum state is dependent on which one or more of the one or more qubits are specified. 20. The non-transitory computer readable medium of claim 16, wherein: when executed by the processor the instructions further cause the processor to perform: receiving input defining a second quantum computing operation to be performed by the quantum computing emulation device to transform a result of the first quantum computing operation; providing the input defining the second quantum computing operation to the quantum computing emulation device as one or more pairs of DC values; and the digital signal represents a modified quantum state as transformed by the performance of the first quantum computing operation and the second quantum computing operation by the quantum computing emulation device.