You use this quantum technology every day without knowing it!

At first glance, it may seem that the concepts of quantum technology only make sense in advanced laboratories or in huge projects of particle physics, but the fact is that every day, without paying attention, we deal with one of the most fundamental phenomena of quantum mechanics, that is, “Quantum Tunneling” and this issue is so important that the 2025 Nobel Prize in Physics was dedicated to it!

Quantum tunneling is actually the basis of solid state memory such as flash memory, SD memory card and solid state drives (SSD) that have become an integral part of today’s digital life. But how does a quantum phenomenon happen outside the laboratory and inside the devices of daily life? To understand this issue, we have to go to the same quantum laboratories that discovered this phenomenon!

What is quantum tunneling?

Now we go to the heart of the quantum world, where particles on the smallest scale have their own governing laws of physics. Laws that do not fit well with classical physics. In classical mechanics, if a particle collides with an obstacle and its energy is less than the energy required to overcome the height of the obstacle, it cannot pass through it. But in the quantum world, electrons behave unpredictably and even when they are at a lower energy level than the barrier, they can still pass through the barrier! This is an amazing phenomenon Quantum tunneling is

Simply put, quantum tunneling
Credit: Cosmos Magazine

It should be said that in subatomic scales, particles are not like small balls, but have a wave-like state. The “wave function” of the electron describes the probability of its presence in different places, and if this function has a non-zero value, even on the other side of the barrier, there is a possibility of the electron passing through the barrier. This is why electrons can pass through very thin layers of insulation. This is the basis used directly in semiconductor memories.

From Theory to Reality: A History of Quantum Tunneling

The phenomenon of tunneling was first proposed in the 1920s at the same time as the foundation of quantum mechanics. Great physicists including Niels Bohr, Werner Heisenberg and Erwin Schrodinger were trying to explain the behavior of particles at atomic scales. But in 1928, George Gamow was able to describe the tunneling phenomenon with a more detailed analysis to explain nuclear decay. where alpha particles, even if their energy is not enough to cross the potential barrier, are emitted from the nucleus of atoms.

In the following decades, the concept of quantum tunneling went beyond the level of theory. In 1958, physicists Leo Esaki, Ivar Giaever, and Brian Josephson investigated the role of this phenomenon in superconducting and semiconducting materials. In this way, their research became the basis for the construction of tools to control and control quantum tunneling. Among these technologies, we can mention “Tunnel Diode” and later “Flash Transistors”.

From right: Josephson, Giver, Isaki
Credit: Cosmos Magazine, United Press, IBM

This technology is so revolutionary that half of the 1973 Nobel Prize in Physics was awarded to Isaki and Giver for their experimental discoveries about the tunneling phenomenon in semiconductors and superconductors, and the other half to Josephson for theoretical predictions about the properties of a supercurrent passing through a barrier, especially the so-called Josephson effects. Now in 2025, after more than half a century, a new generation of scientists won the Nobel Prize in Physics for developing technologies based on this phenomenon; The technologies at the heart of most of our electronic devices.

Quantum tunneling in flash memory and SSD

To understand the role of tunneling in solid state storage, we need to understand that flash memories are made up of millions of memory cells. Each cell is essentially a “field effect transistor” (MOSFET) with an insulating layer of silicon oxide (SiO₂). In normal memories, electrons cannot pass through this layer, but in flash memories, the thickness of the layer is a few nanometers and so small that the quantum tunneling phenomenon occurs and allows electrons to pass through.

Inside each memory cell, there are two important areas: “Floating Gate” and “Control Gate”. When we want to write data into the memory (programming process), a high voltage is applied to the control gate. This voltage creates a strong electric field that causes them to pass through the oxide layer and enter the floating gate by a process known as “Fowler-Nordheim Tunneling”.

How flash memory works
Credit: Spiceworks

The presence or absence of these electrons in the floating gate determines which bit is stored 1 or 0 be When reading data, the circuit detects whether electrons are present in that region and returns the bit value accordingly. In the erasing process, a voltage is applied in the opposite direction so that the electrons tunnel back out of the floating gate. All these processes are done without mechanical parts and this is the feature that made flash memory fast, durable and low consumption.

From flash memory to SSD: The evolution of storage

Quantum tunneling technology was first used in “electronically erasable memories” (EEPROM). In the 1980s, with the improvement of the manufacturing process and the reduction of the thickness of the oxide layer, NAND and NOR flash memories were introduced, which were able to store data without the need for constant energy and were much more resistant to mechanical shock.

Over time, this technology entered computers on a larger scale and revolutionized storage speed and stability in the form of SSD drives. SSD drives also use the same tunneling phenomenon to write and erase information, but this time in multilayer structures (3D NAND) that contain millions of cells per cubic millimeter. Thus, quantum tunneling is no longer just a laboratory phenomenon; Rather, it is the backbone of modern storage technologies.

Using 3D quantum tunnel structures in SSD
Credit: Storedbits, Digikala Mag

Today, this technology is even used in smartphones. The internal memory of phones, both UFS type in new models and eMMC in older models, are originally built on the basis of NAND Flash and its performance depends on the phenomenon of quantum tunneling. This is why mobile phones can hold data without a constant power source and store or retrieve information at high speed.

Commercial pioneers of quantum tunneling

Although the phenomenon of quantum tunneling was theoretically known in the middle decades of the 20th century, its application in the form of flash memories was the result of the efforts of Toshiba and the Japanese engineer Fujio Masuoka. In the early 1980s, he was able to develop the prototype of EEPROM and then NAND Flash memory by designing memory cells based on Fowler-Nordheim tunneling. The achievement that led to the introduction of the first NAND flash chip by Toshiba in 1987 and marked the evolution of data storage.

At about the same time, Intel developed another type of this technology called NOR Flash, which enabled the direct execution of code from the chip. Later, with the entry of companies such as Samsung, Micron, and the Korean company SK Hynix, flash technology was upgraded from two-dimensional cells to three-dimensional structures, and the capacity and durability of memories multiplied to make quantum research of the 20th century one of the most profitable and widely used technologies of the 21st century.

Toshiba has a key role in the development of today’s memories.
Credit: Toshiba

Nobel Physics 2025

The winners of the 2025 Nobel Prizes in Physics are researchers who have been able to develop more precise control methods for quantum tunneling in semiconductor structures. This achievement has helped to make chips with lower power consumption and higher speed. Their research has made future memories not only smaller and faster, but also with decades of data stability. According to the Nobel Committee, these developments have removed the boundary between basic science and everyday technology, and have made a phenomenon that once seemed only theoretical, now in our pockets!

Winners of Nobel Prize in Physics 2025
Credit: Nobel Prize

The future of tunneling technology

Scientists are now investigating ways to combine quantum tunneling with two-dimensional materials such as graphene and molybdenum disulfide (MoS₂) to produce memories with faster write speeds and greater stability. Also, the idea of ​​real “Quantum Memory” is being developed; Where information is not stored as zeros and ones, but in “superposition” states. With this trend, technologies that were once limited to physical theories are now on track to shape the future of computing, data storage, and human life.

Companies like WeLink are pioneering the development of commercial quantum memory.
Credit: Welinq

summary

Quantum tunneling, which once made sense only in Schrödinger’s equations and theoretical models of physics, today beats at the heart of digital devices. From small flash memory to carry information, to SSD memories that determine the speed of modern computers, all work thanks to this subtle and amazing phenomenon. This is one of the fascinating effects of physics that flows in life and now you know that every time you save a file in a memory or take a digital photo, you are actually taking advantage of one of the most mysterious effects of quantum physics.

Sources: MIT, 3D InCites, IEEE, Phys.Org