Another example from atomic physics:

• Orbital excitation blockade and algorithmic cooling in quantum gases. WS Bakr et al. Nature 480, 500 (2011), arXiv:1105.5834.

You start with a large atomic cloud loaded into an optical lattice. Some lattice sites have just one atom, some other lattice sites may have more than one atom. Because of interaction between atoms, an interband transition for singly-occupied site and multiply-occupied site becomes spectroscopically distinguishable. Using this, you can excite one atom from multiply-occupied site into an excited band (more weakly trapped) and remove them, while singly-occupied sites are left unaffected. After this "algorithmic cooling", all the lattice sites are singly-occupied.

Now if you want to select just one site, you can probably use a high-resolution microscope to select a specific singly-occupied site. Even if the resolution of your microscope is not enough to resolve a single lattice site (Airy radius > lattice constant), you can still achieve a sub-diffraction resolved addressing (arXiv:1101.2076). The trick is to combine spatially-varying detuning (AC stark shift from a laser) with a sharp transition (microwave transition).

Another example from atomic physics:

• Orbital excitation blockade and algorithmic cooling in quantum gases. WS Bakr et al. Nature 480, 500 (2011), arXiv:1105.5834.

You start with a large atomic cloud loaded into an optical lattice. Some lattice sites have just one atom, some other lattice sites may have more than one atom. Because of interaction between atoms, an interband transition for singly-occupied site and multiply-occupied site becomes spectroscopically distinguishable. Using this, you can excite one atom from multiply-occupied site into an excited band (more weakly trapped) and remove them, while singly-occupied sites are left unaffected. After this "algorithmic cooling", all the lattice sites are singly-occupied. (Note: term "cooling" is used because the randomly multiply-occupied sites store entropy in the system under study.)

Now if you want to select just one site, you can probably use a high-resolution microscope to select a specific singly-occupied site. Even if the resolution of your microscope is not enough to resolve a single lattice site (Airy radius > lattice constant), you can still achieve a sub-diffraction resolved addressing. The trick is to combine spatially-varying detuning (AC stark shift from a laser) with a sharp transition (microwave transition).

• Single-spin addressing in an atomic Mott insulator. C Weitenberg et al. Nature 471, 319 (2011), arXiv:1101.2076.

Another example from atomic physics: https://arxiv.org/pdf/1105.5834.pdf

You start with a large atomic cloud loaded into an optical lattice. Some lattice sites have just one atom, some other lattice sites may have more than one atom. Because of interaction between atoms, an interband transition for singly-occupied site and multiply-occupied site becomes spectroscopically distinguishable. Using this, you can excite one atom from multiply-occupied site into an excited band (more weakly trapped) and remove them, while singly-occupied sites are left unaffected. After this "algorithmic cooling", all the lattice sites are singly-occupied.

Now if you want to select just one site, you can probably use a high-resolution microscope to select a specific singly-occupied site. Even if the resolution of your microscope is not enough to resolve a single lattice site (Airy radius > lattice constant), you can still achieve a sub-diffraction resolved addressing (https://arxiv.org/abs/1101.2076). The trick is to combine spatially-varying detuning (AC stark shift from a laser) with a sharp transition (microwave transition).

Another example from atomic physics:

• Orbital excitation blockade and algorithmic cooling in quantum gases. WS Bakr et al. Nature 480, 500 (2011), arXiv:1105.5834.

You start with a large atomic cloud loaded into an optical lattice. Some lattice sites have just one atom, some other lattice sites may have more than one atom. Because of interaction between atoms, an interband transition for singly-occupied site and multiply-occupied site becomes spectroscopically distinguishable. Using this, you can excite one atom from multiply-occupied site into an excited band (more weakly trapped) and remove them, while singly-occupied sites are left unaffected. After this "algorithmic cooling", all the lattice sites are singly-occupied.

Now if you want to select just one site, you can probably use a high-resolution microscope to select a specific singly-occupied site. Even if the resolution of your microscope is not enough to resolve a single lattice site (Airy radius > lattice constant), you can still achieve a sub-diffraction resolved addressing (arXiv:1101.2076). The trick is to combine spatially-varying detuning (AC stark shift from a laser) with a sharp transition (microwave transition).