The brand-new strategy, called quantum microscopy by coincidence, includes the entanglement of photons, which act as biphotons with double the momentum of a single photon. Jointly, two entangled photons are understood as a biphoton, and, importantly for Wangs microscopy, they act in some methods as a single particle that has double the momentum of a single photon.
Utilizing a series of mirrors, lenses, and prisms, each biphoton– which in fact consists of two discrete photons– is divided up and shuttled along 2 courses, so that one of the paired photons passes through the object being imaged and the other does not. The photon passing through the things is called the signal photon, and the one that does not is called the idler photon. These photons then continue along through more optics till they reach a detector linked to a computer system that constructs an image of the cell based on the information brought by the signal photon.
Researchers at Caltech have used quantum entanglement to double the resolution of light microscopic lens. The new strategy, called quantum microscopy by coincidence, involves the entanglement of photons, which serve as biphotons with double the momentum of a single photon. This results in a much shorter wavelength, enabling the microscopic lense to attain greater resolution without damaging the specimens being observed, such as living cells. The team built an optical device that used a special crystal to convert photons into biphotons and demonstrated microscopic resolution and cell imaging with their ingenious system.
Caltech researchers have doubled the resolution of light microscopes utilizing quantum entanglement, enabling higher-resolution imaging without damaging specimens like living cells.
Using a “spooky” phenomenon of quantum physics, Caltech scientists have found a method to double the resolution of light microscopic lens.
In a paper released on April 28 in the journal Nature Communications, a team led by Lihong Wang, Bren Professor of Medical Engineering and Electrical Engineering, shows the accomplishment of a leap forward in microscopy through what is called quantum entanglement. Quantum entanglement is a phenomenon in which two particles are connected such that the state of one particle is connected to the state of the other particle no matter whether the particles are anywhere near each other. Albert Einstein notoriously referred to quantum entanglement as “scary action at a range” since it might not be described by his relativity theory.
The quantum microscopy by coincidence (QMC) device. Credit: Caltech
According to quantum theory, any type of particle can be entangled. When it comes to Wangs brand-new microscopy method, dubbed quantum microscopy by coincidence (QMC), the entangled particles are photons. Jointly, 2 knotted photons are understood as a biphoton, and, significantly for Wangs microscopy, they behave in some ways as a single particle that has double the momentum of a single photon.
Because quantum mechanics states that all particles are likewise waves, and that the wavelength of a wave is inversely associated to the momentum of the particle, particles with bigger momenta have smaller wavelengths. Because a biphoton has double the momentum of a photon, its wavelength is half that of the individual photons.
Zhe He (Postdoctoral Scholar Research Associate in Medical Engineering Andrew and Peggy Cherng Dept of Medical Engineering) and Lihong Wang (Bren Professor of Medical Engineering and Electrical Engineering; Andrew and Peggy Cherng Medical Engineering Leadership Chair; Executive Officer for Medical Engineering). Credit: Caltech
This is key to how QMC works. A microscopic lense can only image the functions of an item whose minimum size is half the wavelength of light utilized by the microscope. Lowering the wavelength of that light suggests the microscope can see even smaller things, which results in increased resolution.
Quantum entanglement is not the only method to lower the wavelength of light being used in a microscopic lense. Thumbs-up has a shorter wavelength than traffic signal, for instance, and purple light has a shorter wavelength than thumbs-up. However due to another peculiarity of quantum physics, light with much shorter wavelengths carries more energy. So, as soon as you get down to light with a wavelength small adequate to image small things, the light brings a lot energy that it will harm the items being imaged, particularly living things such as cells. This is why ultraviolet (UV) light, which has a really short wavelength, provides you a sunburn.
A diagram of the quantum microscopy by coincidence device. Credit: Caltech
QMC navigates this limitation by utilizing biphotons that bring the lower energy of longer-wavelength photons while having the shorter wavelength of higher-energy photons.
” Cells dont like UV light,” Wang says. “But if we can utilize 400-nanometer light to image the cell and attain the result of 200-nm light, which is UV, the cells will more than happy, and were getting the resolution of UV.”
To attain that, Wangs group developed an optical apparatus that shines laser light into an unique kind of crystal that transforms some of the photons going through it into biphotons. Even using this unique crystal, the conversion is very rare and happens in about one in a million photons. Using a series of mirrors, lenses, and prisms, each biphoton– which actually consists of two discrete photons– is broken up and shuttled along two paths, so that one of the paired photons passes through the things being imaged and the other does not. The photon going through the things is called the signal photon, and the one that does not is called the idler photon. These photons then continue along through more optics until they reach a detector linked to a computer that builds a picture of the cell based on the info brought by the signal photon. Astonishingly, the paired photons remain entangled as a biphoton acting at half the wavelength in spite of the existence of the item and their different pathways.
Images produced by basic microscopy and quantum microscopy. Credit: Caltech
Wangs lab was not the first to work on this sort of biphoton imaging, but it was the very first to develop a feasible system using the idea. “We established what our company believe a strenuous theory as well as a faster and more accurate entanglement-measurement approach. We reached tiny resolution and imaged cells.”
While there is no theoretical limitation to the number of photons that can be knotted with each other, each additional photon would even more increase the momentum of the resulting multiphoton while more decreasing its wavelength.
Wang states future research study might enable the entanglement of even more photons, although he keeps in mind that each extra photon further minimizes the possibility of an effective entanglement, which, as mentioned above, is already as low as a one-in-a-million possibility.
Referral: “Quantum microscopy of cells at the Heisenberg limitation” by Zhe He, Yide Zhang, Xin Tong, Lei Li and Lihong V. Wang, 28 April 2023, Nature Communications.DOI: 10.1038/ s41467-023-38191-4.
The paper describing the work, “Quantum Microscopy of Cells at the Heisenberg Limit,” appears in the April 28 problem of Nature Communications. Co-authors are Zhe He and Yide Zhang, both postdoctoral scholar research study associates in medical engineering; medical engineering graduate trainee Xin Tong (MS 21); and Lei Li (PhD 19), formerly a medical engineering postdoctoral scholar and now an assistant teacher of electrical and computer engineering at Rice University.
Funding for the research was supplied by the Chan Zuckerberg Initiative and the National Institutes of Health.