16 June 2023

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12 min read

Have you ever wondered about the seemingly impossible phenomena at the subatomic level? Welcome to the world of quantum tunneling - a process that takes us beyond the familiar realm of classical physics and introduces us to the counterintuitive nature of quantum mechanics.

This revolutionary concept has played an essential role in expanding our comprehension of quantum computing. Quantum tunneling, despite its elusive nature, holds profound significance and has practical applications in multiple fields. Its influence permeates through technology, physics, and even biology.

So, **are you ready to delve deeper into this mysterious quantum world?** Continue reading as we unfold the enigma of quantum tunneling.

The world of physics can essentially be divided into two distinct areas: **classical physics** and **quantum physics**. Understanding both is crucial as we embark on our exploration of quantum tunneling.

Classical physics, the rules we experience in our day-to-day lives, is deterministic. **Think of pushing a ball over a hill** - we can accurately predict the ball's position and speed at any given moment. Classical physics **allows us to trace the trajectory of objects with precision**, from baseballs to planets.

Contrarily, quantum physics, which governs the world of subatomic particles, operates differently. Quantum mechanics introduces us to the **probabilistic nature of reality** - the Heisenberg Uncertainty Principle, which states that **we can never simultaneously know a subatomic particle's exact position and momentum**. This principle is not a limitation of our measuring tools but a fundamental property of quantum particles.

Despite this uncertainty, we aren't entirely left in the dark. Quantum physicists use a **wave function tool to determine the probability of finding a particle in a specific location at a given time**. Intriguingly, waves have the characteristic of not completely halting when they encounter a barrier. Much like how sound waves permeate through a closed door, or sunlight radiates through windows, the wave functions of quantum particles can extend into, and sometimes beyond, barriers.

What's the implication of this? It **suggests that the particles**, bound by the laws of quantum physics, **occasionally end up on the other side of barriers** - a fundamental concept in understanding the 'quantum tunneling effect.' As we continue, remember this paradigm-shifting premise that is the crux of quantum tunneling. This idea catapults us into a new world of understanding where particles do the apparently impossible, thanks to the unique quirks of quantum physics.

Unveiling the field of the subatomic world introduces a paradoxical concept that defies our common sense: particles seemingly able to 'tunnel' through walls. Unlike a familiar scenario in our macroscopic world where a ball without enough energy could not cross a hill, the subatomic particles behave differently. This mysterious event, deeply rooted in the principles of quantum mechanics, is referred to as quantum tunneling.

Contrary to classical expectations, they **penetrate through it and emerge on the other side**. This phenomenon isn't a result of an intense force or a high-speed collision. Instead, it occurs due to the probabilistic nature of quantum mechanics, embodied in what's known as the wave function of a particle.

So, how does quantum tunneling work? When a quantum particle encounters a barrier, its associated wave function doesn't stop at the barrier but extends into and beyond it. Since this wave function describes the likelihood of locating the particle in a given space, **there's always a non-zero probability of the particle being found on the other side of the barrier.** This event forms the core of the quantum tunneling effect, an intriguing showcase of the inherent peculiarity of quantum mechanics with far-reaching implications in various scientific and technological domains.

The concept of quantum tunneling has a fascinating historical journey that has significantly impacted our understanding of the subatomic world. It all began in the early 20th century, during the advent of quantum mechanics.

The English physicist George Gamow introduced quantum tunneling into scientific discussion in 1928. He applied the concept to explain the alpha decay process in atomic nuclei, where an alpha particle manages to escape, or tunnel out, from the potential barrier encircling the nucleus. This pioneering idea challenged classical physics, laying the groundwork for potential barrier tunneling in quantum mechanics.

Fast forward to 1957, when Leo Esaki, a Japanese physicist, **provided the first evidence of quantum tunneling in semiconductors**. He demonstrated that electrons could tunnel through a thin insulating barrier in a semiconductor, leading to a real-life application of quantum tunneling. This ground-breaking discovery significantly influenced modern technology development and earned Esaki the Nobel Prize in Physics in 1973.

The 1980s saw another quantum leap in the applications of tunneling. Gerd Binnig and Heinrich Rohrer invented the Scanning Tunneling Microscope (STM) 1981. This instrument, which **used the quantum tunneling of electrons to image atomic surfaces**, transformed our ability to visualize and manipulate the atomic and molecular world. For this revolutionary invention, Binnig and Rohrer were awarded the Nobel Prize in Physics in 1986.

Quantum tunneling took an even more astounding leap when a 2020 study suggested that it **might occur at speed ****faster than light****.** However, this is still an active research area, with much debate and theoretical work to follow. From alpha decay to modern semiconductors, these historical milestones highlight the broad impact and significance of quantum tunneling in the scientific world.

Peering into the mathematical underpinnings of quantum tunneling, we uncover the true beauty of this phenomenon. The mathematical framework allows us to grasp the superficially counterintuitive behaviors in the quantum world. We're not merely dealing with particles anymore; we encounter a universe of probabilities and waves. This mathematics-heavy world, though complex, can offer incredibly accurate predictions about subatomic events, like those involved in quantum tunneling. Let's set sail on this intricate mathematical journey, diving into wave functions, probabilities, and the transformative Schrödinger equation, which acts as our compass in the ocean of quantum tunneling.

When it comes to explaining quantum tunneling, one of the indispensable tools is the Schrödinger equation. Invented by Austrian physicist Erwin Schrödinger, this equation serves as the cornerstone of quantum mechanics, providing a probabilistic framework for particle behavior. **The solutions of this equation, we uncover the idea of a wave function**, which captures the probability distribution of a particle's position. Interestingly, the wave function doesn't completely nullify when it encounters a barrier - instead, it declines exponentially. This gives rise to the surprising possibility of a particle being detected on the other side of the barrier without ever having the energy to cross it - a manifestation of quantum tunneling. The Schrödinger equation brings mathematical clarity to this astounding quantum feat.

Understanding quantum tunneling further necessitates a closer look at wave functions and probability density. A wave function is a mathematical description of the quantum state of a particle. This function, **symbolized by the Greek letter psi (ψ)**, encodes all the potential properties of our quantum system. The probability density, on the other hand, is the **square of the absolute value of the wave function**. It gives us the **likelihood of finding a particle in a certain location**. In the context of quantum tunneling, the wave function allows a particle to have a non-zero probability in regions where classical particles wouldn't be found, thus making tunneling feasible. This stark departure from classical norms is fundamental to the quantum world.

In understanding the concept of quantum tunneling, the idea of barriers, specifically energy barriers, is integral. **Imagine a barrier like a hill**. In classical physics, a particle without enough energy **cannot surpass **this hill. However, in the quantum world, things operate differently due to the phenomenon known as 'barrier penetration.'

Energy barriers in quantum mechanics are analogous to potential barriers, often visualized as walls or impediments that particles encounter. The height of these barriers corresponds to the energy required for a particle to surmount them in a classical sense. Yet, through quantum potential, particles exhibit unique behavior. They don't need to surmount or possess the energy to overcome the barrier. They can instead employ quantum tunneling, **allowing them to seemingly pass through the barrier.**

Regarding tunneling problems, the question often posed is, **“What is the probability of a quantum particle penetrating an energy barrier?”** To answer this, we turn to the Schrödinger equation and the wave function. While a classical particle's energy determines whether it can pass a barrier, the quantum wave function extends through and beyond the barrier, embodying the principle of potential barrier tunneling.

This ability of quantum particles to tunnel through barriers gives rise to the 'quantum tunneling effect' - a testament to the quirky and counterintuitive rules of quantum mechanics. As we progress, remember that barriers in quantum mechanics are not the insurmountable obstacles they appear to be. They are merely a stage for the incredible phenomenon of quantum tunneling to play out.

Although it might seem like an abstract concept deeply rooted in the intricate world of quantum mechanics, this phenomenon has far-reaching implications that touch our everyday lives. This section aims to bridge the gap between the quantum and the tangible, unveiling how the seemingly arcane 'quantum tunneling effect' works in several everyday phenomena. From powering modern electronic devices to facilitating vital biological processes, the influence of quantum tunneling is much more ubiquitous than one might initially suspect. Let's embark on this intriguing exploration of how this quantum marvel permeates our everyday reality.

The application of quantum computing to solve optimization challenges stands at the forefront of advanced computation. Fundamental to this endeavor are qubits, the core components of quantum computation. These qubits possess the remarkable ability to exist in superpositions of both 0 and 1 states, simultaneously exploring multiple solutions—an edge over classical bits.

Recent quantum computing progress has led to greater control over larger qubit arrays, enabling the manipulation of intricate superposition states. Advances in extending qubit coherence durations further enhance the stability of quantum states, rendering them viable for real-world applications like optimization and cryptography.

**Qubits & Superposition:**At the heart of quantum computing lie qubits, which are remarkable for their ability to simultaneously be in both 0 and 1 states. This dual state, known as superposition, broadens their representation capabilities, allowing them to process many potential solutions concurrently. Recent breakthroughs in quantum computing have shown that bigger qubit arrays may be successfully handled and controlled, allowing for more complicated superposition states. Furthermore, researchers have made progress toward increasing the coherence duration of qubits, which improves the stability of quantum states and makes them suitable for practical applications such as optimization issues and cryptography tasks.**Visualization of Optimization**: Consider optimization issues as vast terrains filled with peaks and valleys. The ultimate goal is to identify the deepest valley, which signifies the global minimum. However, traditional algorithms often need to catch up, settling on shallower valleys or local minima, mistaking them for the best solutions.**Tunneling Advantage:**Quantum mechanics introduces a game-changer, the ability of states to "tunnel" through barriers rather than being hindered by them. This means quantum systems can traverse and investigate more of the landscape and reach optimal solutions with increased speed.**Practical Implementation:**Quantum annealing is a technique that capitalizes on this principle. In nature, objects tend to move toward their lowest energy state, like water flowing downhill or heat dispersing. This concept extends to quantum systems. A prominent advocate, D-Wave Systems, utilizes quantum annealers to transform complex optimization problems into energy landscapes. The subsequent objective is to pinpoint the lowest energy state, which signifies the optimal solution.**Limitations and Challenges:**The potential of quantum tunneling in optimization continues to be extensively investigated, yet challenges remain. Due to noise, current quantum systems are mistake-prone, needing developments in error correction. Maintaining sustained speedup over traditional systems is a continuous problem. While quantum systems have the potential to revolutionize problem solutions, the area is evolving as a result of ongoing research and development.

The pursuit of utilizing quantum computing to address optimization problems presents a captivating frontier in advanced computation. Recent advancements in handling larger qubit arrays and extending their coherence durations underscore the practical potential of quantum solutions. Despite challenges like noise and speed sustainability, ongoing research and development are shaping a dynamic landscape with the promise to revolutionize problem-solving methodologies.

The marvel of quantum tunneling plays a critical role in nanotechnology, particularly in tools such as the Scanning Tunneling Microscope (STM). This sophisticated device uses the principles of quantum tunneling to **map out the topography of surfaces at the atomic level**, providing a detailed visualization of atomic and molecular arrangements.

Moreover, Quantum Tunneling Composite (QTC) materials showcase another practical utilization of tunneling. These are** smart materials that change their electrical resistance under pressure**, an effect largely attributed to the tunneling of electrons between the filler particles. From transforming our understanding of material structures to enabling smart, responsive technologies, quantum tunneling's influence in nanotechnology is profound and continues to drive advancements in the field.

The intriguing intersection of quantum physics and biology has shed light on unexpected phenomena within our DNA. Research suggests that our DNA's complex processes, such as replication and mutation, might involve protons "hopping" from one location to another, overcoming an energy barrier larger than their kinetic energy.

This unexpected "hopping" motion manifests quantum tunneling, **enabling the proton to access regions classically considered forbidden.** These tunneling events can potentially lead to mutations, influencing species' evolution over time. This insight, indicating the influence of quantum mechanics in biological processes, has been instrumental in nurturing the burgeoning field of quantum biology.

Exploring these quantum influences on biological processes could revolutionize our understanding of life at its fundamental molecular level. Thus, the phenomenon of quantum tunneling holds implications not only for comprehending subatomic particles but also for deciphering life's intricate complexities.

One of the earliest and most compelling demonstrations of quantum tunneling comes from nuclear physics, specifically in the process of radioactive decay. Alpha decay, a type of radioactive decay, relies heavily on the concept of quantum tunneling.

In alpha decay, **an unstable atomic nucleus releases an alpha particle**, which is confined within a potential well created by nuclear forces. Classically, the alpha particle wouldn't have enough energy to overcome this well. However, quantum mechanics offers a different perspective.

The alpha particle can "tunnel" through this potential barrier, thanks to quantum tunneling,even with insufficient energy to surpass it classically. **This ability of alpha particles to escape from the nucleus through quantum tunneling is a fundamental mechanism behind the phenomenon of radioactive decay.**

The speed of quantum tunneling has been a subject of much debate. For many years, scientists have attempted to measure the duration of the tunneling process, producing varied and sometimes contentious results. Some have even proposed that tunneling might surpass the speed of light. However, a ground-breaking, **20-year-long study**** led by physicists from the Canadian Institute for Advanced Research** has made significant strides in this field.

The team employed rudimentary principles of quantum physics in their innovative experiment. They used 8,000 rubidium atoms, cooled to a temperature near absolute zero, to prevent random, high-speed motion. Then, they used a laser to form a barrier calibrated to a thickness of approximately 1.3 micrometers (about 2,500 rubidium atoms thick). The rubidium atoms were then pushed toward this barrier using another laser, maintaining a steady speed of about 0.15 inches (3.8 mm) per second. While most of the atoms rebounded off the barrier, **roughly 3% successfully tunneled through**, courtesy of our enigmatic friend, quantum tunneling.

The scientists' choice of rubidium was deliberate, as lasers can alter the spin of the atom. The duration of the tunneling process would affect the atom's spin, enabling scientists to measure the time it took for atoms to tunnel by comparing the spin axis before and after the barrier. **The result? An average of ****0.61**** milliseconds.** This outcome is **quite perplexing**, given that it's relatively slow in quantum terms, and previous studies **hinted at the possibility of instantaneous tunneling.**

This significant discovery offers valuable insights into quantum mechanics, **permitting for the first time a tangible measurement of the previously elusive process of quantum tunneling.** The team highlights their ongoing curiosity, stating, "We're working on a new measurement where we make the barrier thicker and then determine the amount of precession at different depths. It will be very interesting to see if the atoms' speed is constant".

Quantum tunneling explained in simple terms: despite its mystifying nature, it plays an essential role in our world and universe. As we deepen our understanding of this quantum phenomenon, it opens new avenues for advancing emergent technologies such as quantum computing. It's exciting to ponder what new quantum phenomena future research will uncover.

Quantum tunneling, once an enigmatic concept restricted to theoretical physics, is now progressively impacting multiple industries, opening new avenues for innovation and discovery. The scientific community's advances in understanding this quantum phenomenon are transforming areas like nanotechnology, biology, and nuclear physics. Additionally, the increased comprehension of tunneling dynamics has vital implications for the burgeoning field of quantum computing.

In this promising context, **BlueQubit**** emerges as an ally** for those eager to delve into the world of quantum computing. Providing a **user-friendly interface** and **state-of-the-art resources**, BlueQubit aims to bridge the gap between complex quantum concepts and practical applications. BlueQubit encourages further exploration and democratization of quantum technology,** by offering an accessible platform to experiment with quantum phenomena, including tunneling**, This synergy between theoretical advances and practical applications hints at a future where quantum tunneling's full potential can be realized, leading to unprecedented technological progress.