Quantum-state readout using four-wave mixing
Quantum state readout is achieved using four-wave mixing. A quantum-state carrier, e.g., a cesium 133 atom, is illuminated with a set of three wavelengths. In the event that the atom is in a first quantum state, e.g., an F=3 state of cesium 133, the illumination triggers emission in a first direction from the atom of a fourth wavelength due to four-wave mixing. Detection of the emission in the first direction thus indicates that the atom is in the first quantum state. In an embodiment, failure to detect an emission indicates the atom is in a second quantum state. In other embodiments, a second set of three wavelengths is used to provide a positive indication that the atom is in its second state, e.g., an F=4 state for cesium 133.
1 . A quantum-state readout system comprising:
a laser system for illuminating a quantum-state carrier (QSC) with electromagnetic radiation (EMR) including at least one illumination set of at least three different wavelengths configured to cause the QSC to emit EMR of an emissions wavelength via four-wave mixing while the QSC is illuminated by the at least one illumination set, wherein the at least one illumination set comprises a first illumination set including the at least three different wavelengths, and a second illumination set including a plurality of additional wavelengths configured to cause the QSC to emit EMR of a second emissions wavelength via four-wave mixing while the QSC is illuminated by the second illumination set;
a photodetector system configured to:
generate a first emission determination indicating whether or not EMR of the emissions wavelength, different from each of the at least three different wavelengths of the at least one illumination set, has been detected; and
generate a second emission determination indicating whether or not EMR of the second emissions wavelength has been detected; and
a readout processor for identifying a quantum state of the QSC based on the emission determination configured to:
determine that the QSC was in a first quantum state when the first emission determination indicates that EMR of the emissions wavelength has been detected; and
determine that the QSC was in a second quantum state when the second emission determination indicates that EMR of the second emissions wavelength has been detected.
2 . The quantum-state readout system of claim 1 wherein, the QSC is a four-wave-mixing capable molecular entity, the EMR is in the form of laser beams, and the wavelengths are between 100 nm and 10,000 nm.
3 . The quantum-state readout system of claim 1 wherein the first quantum state is interpreted as a logic 0 and the second quantum state is interpreted as a logic 1.
4 . The quantum-state readout system of claim 1 wherein the QSC is a cold neutral alkali metal or alkaline-earth-metal atom.
5 . The quantum-state readout system of claim 4 wherein the QSC is a rubidium, cesium, or strontium atom.
6 . The quantum-state readout system of claim 1 , wherein the at least three different wavelengths are configured to cause the QSC to emit the EMR of the emissions wavelength only when EMR at each of the at least three different wavelengths are concurrently illuminating the QSC.
7 . The quantum-state readout system of claim 1 , wherein a direction of the EMR of the emissions wavelength results from a combination of momentum vectors for the EMR at each of the at least three different wavelengths.
8 . The quantum-state readout system of claim 1 , wherein the EMR of the emissions wavelength is emitted anisotropically.
9 . A method comprising:
illuminating, using a laser system, a quantum-state carrier (QSC) with electromagnetic radiation (EMR) including at least one illumination set of at least three different wavelengths configured to cause the QSC to emit EMR of an emissions wavelength via four-wave mixing while the QSC is illuminated by the at least one illumination set, wherein the at least one illumination set comprises a first illumination set including the at least three different wavelengths, and a second illumination set including a plurality of additional wavelengths configured to cause the QSC to emit EMR of a second emissions wavelength via four-wave mixing while the QSC is illuminated by the second illumination set;
generating, using a photodetector system, a first emission determination indicating whether or not EMR of the emissions wavelength, different from each of the at least three different wavelengths of the at least one illumination set, has been detected; and
generating, using the photodetector system, a second emission determination indicating whether or not EMR of the second emissions wavelength has been detected; and
determining, using a readout processor, that the QSC was in a first quantum state when the first emission determination indicates that EMR of the emissions wavelength has been detected; and
determining, using the readout processor, that the QSC was in a second quantum state when the second emission determination indicates that EMR of the second emissions wavelength has been detected.
10 . The method of claim 9 , wherein at least a first wavelength of the at least three different wavelengths of the first illumination set is directed onto the QSC from an opposing side of the QSC from the photodetector system.
11 . The method of claim 9 , wherein the QSC is a single atom of rubidium, cesium, or strontium.
12 . The method of claim 9 , wherein each of the at least three different wavelengths of the first illumination set is between 100 nm and 10,000 nm.
13 . The method of claim 9 , wherein the QSC is a physical system with optical non-linearity to generate four-wave-mixing.
14 . The method of claim 13 , wherein the QSC is a neutral atom or an ion.
15 . The method of claim 9 , wherein the first quantum state is interpreted as a logic 0 and the second quantum state is interpreted as a logic 1.
16 . The method of claim 9 , wherein the QSC is a cold neutral alkali metal or alkaline-earth-metal atom.