Quantitative Complementarity in Wave-Particle Duality Challenged by Scientists

At Korea's Institute for Basic Sciences (IBS), researchers Tai Hyun Yoon and Minhaeng Cho put a twist on the classic double-slit experiment, complicating and challenging the principle of complementarity.

Quantitative Complementarity of Wave-Particle Duality

The double slit experiment is one of the most famous experiments in physics, demonstrating the dual nature of fundamental entities such as photons and electrons. When particles pass through two narrow slits, they produce interference patterns on the screen behind the openings.

The interference bands reveal the wave property of photons since only one point of light on the screen is created by a single particle. Once the detectors are positioned at the slits to determine the opening where the photon passes through, the interference band disappears, and the photons demonstrate their particle nature. Both experimental outcomes must be investigated to understand photons' quantum nature fully.

Yoon and Cho added to this principle by proving that the properties of the slits also affect the complementarity of photons. They ejected seed beams of laser light toward two lithium niobate crystals to support their theory. The illuminated crystals produced two types of photons: a signal photon and an idler photon.

The signal photon was sent into an interferometer to produce interference bands and measure the wave property of photons. While doing this, the researchers observed the direction of the idler photon to determine its particle nature. They found out that both the signal and idler photons are created at the same time, forming a single quantum state described by the quantified wave and particle properties.

In past theoretical studies, physicists discovered that photons' wave-ness and particle-ness should be aligned with the equation involving source purity or the likelihood that a crystal source emits light. The experiment made by Yoon and Cho focused on systems where the photon acts partly as a wave and partly as a particle, serving as the pioneer complementarity experiment to control the source purity precisely.

The discoveries made by the researchers prove that photons' controlled and measured duality can be recast. This allows them to link the complementarity to the nature of photons usually exploited in most quantum devices. The result of the study also serves as a breakthrough in quantum physics since it demonstrates the possibility of producing a single photon state in a setting where all the parameters are controlled.

Quantum Theory of Waves and Particles

The debate over the nature of light goes back as early as the 17^th century. Isaac Newton performed experiments in the morning, leading to the corpuscular theory's development. This theory states that light comprises tiny particles called corpuscles, which travel in a straight line. Although this theory can explain the reflection of light, it fails to describe the other properties of light, such as diffraction and interference.

Another scientist named Christian Huygens proposed his wave theory of light, describing light as a wave that vibrates up and down as it travels from one medium to another. This theory successfully allowed Huygens to derive the laws of reflection and refraction of light.

In 1864, James Clerk Maxwell discovered the ability of electric and magnetic fields to travel through space at the same speed as that of light. He called this the theory of electromagnetism, describing light as a propagating wave of electric and magnetic fields.

Finally, German theoretical physicist Max Planck proposed that light exists as small massless entities called photons, which demonstrate the wave-particle duality, having the properties of both a particle and a wave.