There is an ensemble qubit which contain a large number of particles that together act as a single qubit and there is what one typically thinks of as a qubit, which is a single particle or material.
Possible qubits include single photons, trapped atomic ions, neutral atoms, nuclear spins, quantum dots, impurities in silicon and diamond, etc...
WHAT IS THE MEANING OF QUANTUM OR QUANTA?
When we talk about physics, it is likely that quantum or quanta would be mentioned. So, what is it?
Well, it comes from the Latin word “Quantus”, which means “amount”. It is the smallest discrete unit of any physical property. As there is a minimum amount, this means that these properties comes in discrete amounts. So, these properties are quantized. For example, the single quantum of light is called photon.
This term has been used from 1900 when a physicist named Max Planck used it in one of his presentations. During that time, he wanted to discover why a glowing body’s radiation changes from red to orange and then finally, to blue with the increase in temperature. So, he wrote a mathematical equation that involves a figure used to represent units of energy individually. He found out that at a certain discrete level of temperature, the energy coming from a glowing body occupies different color spectrum areas.
He assumed that due to the discovery of quanta, a theory was yet to emerge, but nevertheless, quanta’s existence itself is an implication of a new understanding of the laws of nature. Because of his theory, he won the Nobel Prize in Physics in 1918.
On the other hand, our understanding of quantum/quanta now is also the combination of the contributions of other scientists like Hermann von Helmholtz, who used the work in the field of electricity. He used ‘quanta’ with reference to heat in his articles, while Julius von Mayer used the word ‘quantum’ in his letter regarding the formulation of the first law of thermodynamics.
In 1905, Albert Einstein created a theory that energy is not the only thing that was quantized in the same manner but that radiation itself was quantized as well.
1n the mid 1920’s, Louis de Broglie proposed that no fundamental differences exist between energy and matter’s makeup, and their behavior at the atomic and subatomic level. They actually behave as if they were made up of waves.
QUANTUM / QUANTA
This theory became known as the wave-particle quality theory. It is basically a theory where the matter and energy’s elementary particles behave depending on waves.
On the other hand, Werner Heisenberg proposed that simultaneously measuring two complementary values is possible.
The main idea about a quantum (or quanta in the plural) is that it is the minimum amount of something that can exist.
Nevertheless, oftentimes, it refers to energy. As we all know, energy travels in a matter that is discontinuous and it is comprised of a large number of quanta or tiny discrete units. Like letters in the mail. Not a continuous stream, like water coming out of a tap. Meaning to say, energy is not absorbed continuously. It is absorbed in the form of wave packets instead. Each of these packets are also called quantum that is associated with a definite energy amount.
Now, the word ‘quantum’ is not only used in physics. In fact, it is also used in other areas, in adjective form, holding a similar meaning as that of the word “infinite”. For example, one might say that waiting for someone is ‘quantumly irritating’, especially if they have waited for hours already.
QUANTUM CRYPTOGRAPHY
Quantum cryptography uses the principles of quantum mechanics to encrypt data. At the subatomic level, particles exist in more than one state due to superposition. By using a method called Quantum Key Distribution (QKD), anybody trying to hack the encryption key will change the particle’s behavior. This will introduce errors into the encoded quantum key and alert others not to use it. It’s a neat trick.
There are also a quantum computer’s obscene processing speeds to -literally - factor in. With their ability to decrypt the very long prime number keys used to encrypt data, the rules of cybersecurity will need to be rewritten. Shor’s quantum algorithm - which detects long strings of periodicities - can apply decryption in minutes. Compare this to the eons that it would take a classical computer using regular cryptography.
