Quantum physics (also called quantum theory or quantum mechanics) is a branch of physics that describes the behavior and interaction between matter and energy at the scale of subatomic particles, photons and some materials at very low temperatures. The quantum realm is defined where the action (or angular momentum) of the particle is contained within a few orders of magnitude of a very small physical constant called Planck's constant.
Steps
Step 1. Understand the physical meaning of Planck's constant
In quantum mechanics, the quantum of action is Planck's constant, often denoted by h. Similarly, for the interaction of subatomic particles, the quantum of angular momentum is the reduced Planck constant (Planck constant divided by 2π) denoted by ħ and called h cut. Note that the value of Planck's constant is extremely small, its units are those of angular momentum, and the notion of action is the most general mathematical concept. As the name quantum mechanics implies, certain physical quantities, such as angular momentum, can only change in discrete quantities, and not continuously (analogically). For example, the angular momentum of an electron bound to an atom or molecule is quantized and can only have values that are multiples of the reduced Planck constant. This quantization generates a series of prime and integer quantum numbers on the orbitals of the electrons. Conversely, the angular momentum of a nearby unbound electron is not quantized. Planck's constant also plays an important role in quantum theory of light, where a quantum of light is represented by the photon and where matter and energy interact through the atomic transition of the electron or "quantum leap" of the bound electron. The units of Planck's constant can also be seen as periods of energy. For example, in the context of physical particles, virtual particles are defined as particles with mass that appear spontaneously from the vacuum for a small fraction of time and play a role in an interaction of particles. The limit to the period of existence of these virtual particles is the energy (mass) of the times of appearance of the particle. Quantum mechanics encompasses a very wide variety of subjects, but every part of its calculations involves the Planck constant.
Step 2. Be aware that particles with mass go through a transition from classical to quantum
Although the free electron exhibits some quantum properties (such as spin), as the unattached electron approaches the atom and slows down (perhaps by emitting photons), it transitions from classical to quantum behavior as soon as its energy falls below the ionization energy. The electron then binds to the atom and its angular momentum, depending on the atomic nucleus, is restricted to the quantized values of the orbitals it can occupy. The transition is sudden. One could compare this transition to that of a mechanical system that changes showing behavior from unstable to stable or from simple to chaotic, or even to a spacecraft that slows down by going below escape velocity and entering orbit around some star or other body. heavenly. Conversely, photons (which are massless) do not go through such a transition: they simply pass through space without change until they interact with other particles and disappear. When you look at a starry night, photons have traveled unchanged from some star across light years of space to interact with an electron in a molecule in your retina, transfer their energy, and then disappear.
Step 3. Know that there are novel ideas in quantum theory, including:
- Quantum reality follows rules that are a little different from the world we experience every day.
- The action (or angular momentum) is not continuous, but occurs in small and discrete units.
- Elementary particles behave both as particles and as waves.
- The motion of a specific particle is random by nature and can only be predicted in terms of probability.
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It is physically impossible to simultaneously measure the position and angular momentum of a particle with the accuracy allowed by Planck's constant. The more precisely one is known, the less accurate the measurement of the other will be.
Understand Quantum Physics Step 4 Step 4. Understand Particle Wave Duality
Assume that all matter exhibits both wave and particle properties. A key concept in quantum mechanics, this duality refers to the inability of classical concepts such as "wave" and "particle" to fully describe the behavior of objects at the quantum level. For a complete knowledge of the duality of matter, one should possess the concepts of the Compton effect, the photoelectric effect, the De Broglie wavelength and Planck's formula for the radiation of black bodies. All these effects and theories prove the dual nature of matter. There are several experiments on light carried out by scientists who prove that light has a dual nature, of particle as well as wave … In 1901, Max Planck published an analysis that was able to reproduce the observed spectrum of light emitted by a bright object. To do this, Planck had to make an ad hoc mathematical conjecture for the quantized action of the oscillating objects (black body atoms) that emitted the radiation. It was then Einstein who proposed that it was the electromagnetic radiation itself that was quantized into photons.
Understand Quantum Physics Step 5 Step 5. Understand the Uncertainty Principle
Heisenberg's Uncertainty Principle states that some pairs of physical properties, such as position and momentum, cannot be known simultaneously with arbitrary high precision. In quantum physics, a particle is described by a packet of waves that gives rise to this phenomenon. Consider measuring the position of a particle, it could be anywhere. The particle's wave packet has a non-zero extent, which means its position is uncertain - it could be pretty much anywhere within the wave packet. To get an accurate position reading, this wave packet must be 'compressed' as much as possible, i.e. it must consist of increasing numbers of the sine of the waves joined together. The momentum of the particle is proportional to the wave number of one of these waves, but it could be any of them. So by making a more precise measurement of position - adding more waves together - inevitably the measurement of momentum becomes less accurate (and vice versa).
Understand Quantum Physics Step 6 Step 6. Understand the wave function
. A wave function in quantum mechanics is a mathematical tool that describes the quantum state of a particle or system of particles. It is commonly applied as a property of particles, relative to their wave-particle duality, denoted by ψ (position, time) where | ψ |2 is equal to the probability of finding the subject at a given time and position. For example, in an atom with only one electron, such as hydrogen or ionized helium, the wave function of the electron provides a complete description of the electron's behavior. It can be decomposed into a series of atomic orbitals that form a basis for possible wave functions. For atoms with more than one electron (or any system with multiple particles), the space below constitutes the possible configurations of all electrons, and the wave function describes the probabilities of these configurations. To solve problems in tasks involving the wave function, familiarity with complex numbers is a fundamental prerequisite. Other prerequisites are linear algebra calculations, Euler's formula of complex analysis and bra-ket notation.
Understand Quantum Physics Step 7 Step 7. Understand the Schrödinger equation
It is an equation that describes how the quantum state of a physical system changes over time. It is as fundamental to quantum mechanics as Newton's laws are to classical mechanics. The solutions to the Schrödinger equation describe not only subatomic, atomic and molecular systems but also macroscopic systems, perhaps even the entire universe. The most general form is the time-dependent Schrödinger equation which describes the evolution over time of a system. For steady-state systems, the time-independent Schrödinger equation is sufficient. Approximate solutions to the time-independent Schrödinger equation are commonly used to calculate the energy levels and other properties of atoms and molecules.
Understand Quantum Physics Step 8 Step 8. Understand the principle of overlap
Quantum superposition refers to the quantum mechanical property of solutions to the Schrödinger equation. Since the Schrödinger equation is linear, any linear combination of solutions to a particular equation will also constitute its solution. This mathematical property of linear equations is known as the superposition principle. In quantum mechanics these solutions are often made orthogonal, like the energy levels of an electron. In this way, the superposition energy of the states is canceled and the expected value of an operator (any superposition state) is the expected value of the operator in the individual states, multiplied by the fraction of the superposition state that is in”That state.
Advice
- Solve high school numerical physics problems as a practice for the work required to solve quantum physics calculations.
- Some prerequisites for Quantum Physics include the concepts of classical mechanics, Hamilton properties and other wave properties such as interference, diffraction, etc. Consult suitable textbooks and reference books or ask your physics teacher. You should achieve a solid understanding of high school physics and its prerequisites as well as learn a good bit of college-level math. To get an idea, see the table of contents on Schaums Outline.
- There are online lecture series regarding quantum mechanics on YouTube. See
