Methods and apparatuses for identifying and controlling quantum emitters in a quantum system
The disclosure describes an adaptive and optimal imaging of individual quantum emitters within a lattice or optical field of view for quantum computing. Advanced image processing techniques are described to identify individual optically active quantum bits (qubits) with an imager. Images of individual and optically-resolved quantum emitters fluorescing as a lattice are decomposed and recognized based on fluorescence. Expected spatial distributions of the quantum emitters guides the processing, which uses adaptive fitting of peak distribution functions to determine the number of quantum emitters in real time. These techniques can be used for the loading process, where atoms or ions enter the trap one-by-one, for the identification of solid-state emitters, and for internal state-detection of the quantum emitters, where each emitter can be fluorescent or dark depending on its internal state. This latter application is relevant to efficient and fast detection of optically active qubits in quantum simulations and quantum computing.
1. A method for identification of optically active quantum systems that include one or more individual quantum emitters, comprising:
providing an optical source that produces fluorescence from the quantum emitters as the quantum emitters are loaded into a trap, each of the quantum emitters behaving as an optical object having a certain intensity distribution in response to the fluorescence;
identifying a position of each of the quantum emitters by fitting an overall intensity distribution to a sum of a variable number of Gaussian functions; and
controlling, in real-time, a number of the quantum emitters that are loaded into the trap based at least on the identified positions of each of the quantum emitters and whether one or more of the quantum emitters are not fluorescing in response to the fluorescence.
2. The method of claim 1 , wherein each of the quantum emitters is an atom or a solid-state quantum emitter.
3. The method of claim 1 , wherein the identifying of the position of each of the quantum emitters by fitting the overall intensity distribution to the sum of the variable number of Gaussian functions comprises determining peak positions in the overall intensity distribution by calculating the Laplacian of Gaussians whose zeros indicate an inflection point of an intensity distribution for each peak.
4. The method of claim 3 , wherein a difference of Gaussians algorithm is used to approximate the Laplacian of Gaussians.
5. The method of claim 1 , wherein the identifying of the position of each of the quantum emitters by fitting the overall intensity distribution to the sum of the variable number of Gaussian functions produces regions of local maxima corresponding to a centroid in position of each of the quantum emitters.
6. The method of claim 1 , wherein the identifying of the position of each of the quantum emitters by fitting the overall intensity distribution to the sum of the variable number of Gaussian functions comprises:
determining a relative spacing between quantum emitters based on a number of quantum emitters to be trapped in the trap;
determining an initial and approximate position of each of the quantum emitters based on the relative spacing; and
identifying the position of each of the quantum emitters based at least in part of the initial and approximate position of each of the quantum emitters.
7. The method of claim 6 , further comprising computing the relative spacing for a lattice of up to 10 quantum emitters, up to 20 quantum emitters, up to 30 quantum emitters, up to 40 quantum emitters, up to 50 quantum emitters, up to 60 quantum emitters, up to 70 quantum emitters, up to 80 quantum emitters, up to 90 quantum emitters, or up to 100 quantum emitters.
8. The method of claim 6 , further comprising computing the relative spacing for a lattice having a one-dimensional (1D) conformation, a two-dimensional (2D) conformation, or a three-dimensional (3D) conformation.
9. The method of claim 1 , further comprising performing a corrective action when the number of quantum emitters that are loaded into the trap is not a correct number, when an incorrect quantum emitter species is loaded into the trap, or when one or more of the quantum emitters loaded into the trap cannot be properly initialized.
10. A quantum information processing (QIP) system, comprising:
a quantum emitter lattice having one or more individual quantum emitters;
an optical controller configured to provide an optical source that produces fluorescence on the quantum emitters as the quantum emitters are loaded into the quantum emitter lattice, each of the quantum emitters behaving as a point-source optical object having a certain intensity in response to the fluorescence; and
an imaging system configured to:
identify a position of each of the quantum emitters by fitting an overall intensity distribution to a sum of a variable number of Gaussian functions; and
control, in real-time, a number of quantum emitters that are loaded into the quantum emitter lattice based at least on the identified positions of each of the quantum emitters and whether any of the quantum emitters is not fluorescing in response to the fluorescence.
11. The QIP system of claim 10 , wherein each of the quantum emitters is an atom, an ion, or a solid-state quantum emitter.
12. A non-transitory computer-readable medium storing code with instructions executable by a processor for identification of quantum emitters, comprising:
code for providing an optical source that produces fluorescence on the quantum emitters as the quantum emitters are loaded into a lattice, each of the quantum emitters behaving as a point-source optical object having a certain intensity in response to the fluorescence;
code for identifying a position of each of the quantum emitters by fitting an overall intensity distribution to a sum of a variable number of Gaussian functions; and
code for controlling, in real-time, a number of quantum emitters that are loaded into the lattice based at least on the identified positions of each of the quantum emitters and whether any of the quantum emitters is not fluorescing in response to the fluorescence.
13. A method for identification of optically active quantum systems that include one or more individual quantum emitters, comprising:
providing an optical source that produces fluorescence from the quantum emitters within an optical field of view, each of the quantum emitters behaving as an optical object having a certain intensity distribution in response to the fluorescence;
identifying a position of each of the quantum emitters by fitting an overall intensity distribution to a sum of a variable number of Gaussian functions; and
controlling, in real-time, a number of quantum emitters that are within the field of view based at least on the identified positions of each of the quantum emitters and whether one or more of the quantum emitters are not fluorescing in response to the fluorescence.
14. The method of claim 13 , wherein each of the quantum emitters is a solid-state quantum emitter.
15. The method of claim 14 , wherein the solid-state quantum emitter is a quantum dot.