By observing the current, the distance can be kept fairly constant, allowing the tip to move up and down according to the structure of the sample.
As such, observing an atom's wave function and getting an image of its full quantum state requires many measurements to be made, which are then statistically averaged.
The principle is to study the spatial distribution of electrons ejected from an atom in a situation in which the De Broglie wavelength becomes large enough to be observed on a macroscopic scale.
The application of an electric field during photoionization allows confining the electron flux along one dimension.
An infinite set of trajectory families lead to a complicated interference pattern on the detector.
The first attempts to use photoionization microscopy were performed on atoms of Xenon by a team of Dutch researchers in 2001.
[1] These trajectories produce a distinct pattern that can be detected by a two-dimensional flux detector and subsequently imaged.
[1] The next group to attempt photoionization microscopy used the excitation of Lithium atoms in the presence of a static electric field.
In 2013, Aneta Stodolna and colleagues imaged the hydrogen atom's wave function by measuring an interference pattern on a 2D detector.
Typically, entanglement of N particles is used to measure a phase with precision ∆φ = 1/N, called the Heisenberg limit.
When the two beams hit the flat surface, they both travel the same length and produce a corresponding interference pattern.
In addition, since the interaction region within entangled microscopy is controlled by two beams, image site selection is flexible, which provides enhanced axial and lateral resolution[17] In addition to biological tissues, high-precision optical phase measurements have applications such as gravitational wave detection, measurement of materials properties, as well as medical and biological sensing.
Squeezed states have been shown to allow a signal-to-noise ratio improvement of as much as a factor of thirty.
of lipid granules that naturally occur within the cell, and that this provided a more accurate measurement[compared to?]
[19] This allowed quantum enhanced resolution to be demonstrated, and for this to be achieved in a far-sub-diffraction limited microscope.
[20] Nonlinear microscopes use intense laser illumination, close to the levels at which biological damage can occur.
This damage is a key barrier to improving their performance, preventing the intensity from being increased and therefore putting a hard limit on SNR.
[clarification needed] By detecting N-photon events, the resolution can be improved by up to a factor of N over the diffraction limit.
In conventional fluorescence microscopes, antibunching information is ignored, as simultaneous detection of multiple photon emission requires temporal resolution higher than that of most commonly available cameras.
[25] Quantum correlations offer an SNR beyond the photo-damage limit (the amount of energy that can be delivered without damage to the sample) of conventional microscopy.
A coherent Raman microscope offers sub-wavelength resolution and incorporates bright quantum correlated illumination.