Quantum lithography is a type of

photolithography In integrated circuit manufacturing, photolithography or optical lithography is a general term used for techniques that use light to produce minutely patterned thin films of suitable materials over a substrate, such as a silicon wafer, to protect ...

, which exploits non-classical properties of the photons, such as

quantum entanglement Quantum entanglement is the phenomenon that occurs when a group of particles are generated, interact, or share spatial proximity in a way such that the quantum state of each particle of the group cannot be described independently of the state of ...

, in order to achieve superior performance over ordinary classical lithography. Quantum lithography is closely related to the fields of

quantum imaging Quantum imaging is a new sub-field of quantum optics that exploits quantum correlations such as quantum entanglement of the electromagnetic field in order to image objects with a resolution or other imaging criteria that is beyond what is possible ...

quantum metrology Quantum metrology is the study of making high-resolution and highly sensitive measurements of physical parameters using quantum theory to describe the physical systems, particularly exploiting quantum entanglement and quantum squeezing. This fie ...

, and quantum sensing. The effect exploits the quantum mechanical state of light called the

NOON state In quantum optics, a NOON state or N00N state is a quantum-mechanical many-body Quantum entanglement, entangled state: : , \psi_\text \rangle = \frac, \, which represents a superposition of ''N'' particles in mode ''a'' with zero particles in ...

. Quantum lithography was invented at Jonathan P. Dowling's group at

JPL The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

, and has been studied by a number of groups. Of particular importance, quantum lithography can beat the classical

Rayleigh criterion Angular resolution describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object, thereby making it a major determinant of image resolution. ...

for the

diffraction Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a s ...

limit. Classical

has an

optical imaging Medical optical imaging is the use of light as an investigational :wikt:imaging, imaging technique for medical applications. Examples include optical microscopy, spectroscopy, endoscopy, scanning laser ophthalmoscopy, laser Doppler imaging, and opti ...

resolution that cannot be smaller than the wavelength of light used. For example, in the use of

to mass-produce computer chips, it is desirable to produce smaller and smaller features on the chip, which classically requires moving to smaller and smaller wavelengths (ultraviolet and x-ray), which entails exponentially greater cost to produce the optical imaging systems at these extremely short optical wavelengths. Quantum lithography exploits the

between specially prepared photons in the

and special

photoresist A photoresist (also known simply as a resist) is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronic industry. T ...

s, that display multi-photon absorption processes to achieve the smaller resolution without the requirement of shorter wavelengths. For example, a beam of red photons, entangled 50 at a time in the NOON state, would have the same resolving power as a beam of x-ray photons. The field of quantum lithography is in its infancy, and although experimental proofs of principle have been carried out using the

Hong–Ou–Mandel effect The Hong–Ou–Mandel effect is a two-photon interference effect in quantum optics that was demonstrated in 1987 by three physicists from the University of Rochester: Chung Ki Hong (홍정기), Zheyu Ou (区泽宇), and Leonard Mandel. The eff ...

, it is still a long way from practical uses.

References

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External links

American Institute of PhysicsIntroduction to Quantum LithographyScience News
Quantum information science Lithography (microfabrication)