Method and apparatus for amplitude estimation of quantum circuit, storage medium, and electronic apparatus

An apparatus for amplitude estimation of a quantum circuit, wherein the apparatus is a computer, a quantum virtual machine is built in the computer by using resources of the computer, a quantum program is running in the quantum virtual machine, the quantum program comprises a quantum circuit, wherein the apparatus for amplitude estimation of a quantum circuit comprises:

• a first difference value calculation module, configured to:
• determine a target quantum state of a target quantum bit in a target quantum circuit, calculate a first difference value between a current angle upper limit value and a current angle lower limit value that are corresponding to a to-be-estimated amplitude of the target quantum state, and determine the first difference value as a target difference;
• an angle factor calculation module, configured to:
• determine, based on a preset intermediate variable parameter, the current angle upper limit value, and the current angle lower limit value, a next angle amplification factor and a next flag parameter that are corresponding to a next iteration step, when the target difference is greater than a preset precision threshold;
• a quantum state measurement module, configured to:
• control a preset amplification quantum circuit to amplify the target quantum circuit by the next angle amplification factor, and measure a target quantum state of the target quantum bit in the amplified target quantum circuit based on a preset total quantity of observation times;
• a second difference value calculation module, configured to:
• calculate a second difference value between a next angle upper limit value and a next angle lower limit value of the to-be-estimated amplitude based on the current angle upper limit value, the current angle lower limit value, the next angle amplification factor, the next flag parameter, and a measurement result of the target quantum state, determine the second difference value as a target difference and repeating the process until the target difference is not greater than the precision threshold;
• and
• a target amplitude estimation module, configured to determine, based on an angle upper limit value and an angle lower limit value that reach the precision threshold, a probability estimated value corresponding to a to-be-estimated quantum bit.