Why should we place importance on the upcoming generation of computers known as quantum computers? To address this query, it is crucial to first comprehend the limitations faced by classical computers in solving combinatorial problems.
But what exactly are combinatorial problems? Are they abstract mathematical equations that hold no practical value? Contrary to this perception, combinatorial problems are encountered in everyday scenarios such as combination locks, residential keys, email passwords, and encryption mechanisms used in online shopping for securing purchase information.
Quantum Computers
Richard Feynman, a noted physicist, stated, “If you think you understand quantum mechanics, you don’t understand quantum mechanics.”
Besides a quantum computer’s ability to crack encryption, a new world of simultaneous simulation of different molecular substance interactions can be modeled. Recent breakthroughs in medicine, material science, artificial intelligence and global warming remediation may well be on the way with the help of quantum computing!
Quantum computers are a highly debated topic among experts, with some believing that they could render most data security protocols obsolete and break the internet, while others see them as a potential solution to the climate crisis through their immense computational power. These devices are considered revolutionary due to their ability to utilize the properties of quantum mechanics. IBM recently unveiled its latest quantum computer, the Osprey, a processor with 433 qubits that is three times more powerful than its 2021 predecessor.
While quantum computers have limitations and cannot solve all problems, they have the potential to make significant advancements in fields such as drug discovery and materials science. Quantum technology supporters are optimistic that these advancements could lead to lighter and more efficient electric vehicle batteries, as well as materials that effectively capture CO2, which are crucial for addressing the ongoing climate crisis.
Given the magnitude of the climate crisis and the potential benefits of quantum technology, it is not surprising that some of the world’s largest tech companies, including Google, Microsoft, Amazon, and IBM, are heavily investing in quantum computing and positioning themselves for a quantum future.
Quantum Qubits vs. Bits
To gain a comprehensive understanding of quantum computing, it is helpful to explore the concept of quantum bits (qubits) and compare their binary equivalency to traditional computer bits. The subsequent table illustrates the data equivalence between qubits and bits, emphasizing their distinctive properties:
Here’s an expanded version of the table that includes comparisons between 1, 2, and 3 qubits and their respective binary equivalents in bits:
| Qubits | Binary Equivalent | Bits |
|---|---|---|
| 1 | 0 | 0 |
| 1 | 1 | 1 |
| 2 | 00 | 0 |
| 2 | 01 | 1 |
| 2 | 10 | 2 |
| 2 | 11 | 3 |
| 3 | 000 | 0 |
| 3 | 001 | 1 |
| 3 | 010 | 2 |
| 3 | 011 | 3 |
| 3 | 100 | 4 |
| 3 | 101 | 5 |
| 3 | 110 | 6 |
| 3 | 111 | 7 |
This table illustrates the correspondence between the number of qubits and the number of possible states (binary equivalents) they can represent. For example, with 1 qubit, there are two possible states (0 and 1), while with 2 qubits, there are four possible states (00, 01, 10, and 11), and so on. The corresponding binary representation in bits is also provided for each qubit configuration.
How do quantum computers work?
The machines that are attracting so much interest have a utopic-sounding quality to them. Therefore, it might be useful to comprehend their workings and how they differ from classical computing.
To start, consider every device currently available, ranging from smartphones to supercomputers. All of these devices have always operated on the same binary code principle.
In essence, the chips in our computers contain tiny transistors that function as on/off switches, representing the two possible values of 0 or 1, known as bits. These bits can be grouped together into more complex units, forming long strings of 0s and 1s that carry encoded data commands, instructing the computer on what to do, such as displaying a video, playing an mp3 file, or allowing you to type an email.
However, a quantum computer functions entirely differently. Instead of bits, the basic unit of information in quantum computing is a quantum bit, or qubit, which is typically a subatomic particle such as an electron or photon.
The advanced computational power of a quantum machine lies in its ability to manipulate these qubits. A qubit is a two-level quantum system that enables quantum information storage.
Superposition
Superposition in qubits refers to the property that a qubit can be in a linear combination of the two classical states, 0 and 1. Specifically, a qubit can be expressed as a superposition of the basis states |0⟩ and |1⟩ as follows:
|ψ⟩ = α|0⟩ + β|1⟩
where α and β are complex amplitudes, and the squared magnitudes of the amplitudes |α|² and |β|² represent the probabilities of measuring the qubit in the states |0⟩ and |1⟩, respectively.
To clarify, in contrast to a classical bit that can only be in one of the two states, 0 or 1, a qubit in superposition can exist in both states simultaneously, which is often referred to as a “quantum superposition.” Therefore, a qubit can be represented as a linear combination of both states, where the probability of observing the qubit in either state depends on the magnitudes and phases of the complex amplitudes.
An analogy often used to explain quantum superposition is that of a penny. When a penny is not moving, it has only two possible outcomes, heads or tails. However, when it is tossed or spun, it can exist in a superposition of both states simultaneously until it lands and a measurement is made, collapsing the superposition to one of the classical states.
The ability to be in multiple states at once allows quantum computers to encode data using exponentially more states than classical computers, which are limited to only two states. This property of quantum systems is what gives quantum computers their potential for exponential speedup in certain computational tasks.
Quantum entanglement
The phenomenon of entanglement is a crucial property that underpins the workings of quantum computing. It is a mysterious feature of quantum mechanics, which even Einstein found puzzling, referring to it as “spooky action at a distance”. When two qubits are created in an entangled state, there is a direct and measurable correlation between their behavior, no matter how far apart they are. This correlation does not have an equivalent in the classical world.
The importance of entanglement lies in its ability to create a much stronger connectivity between the different units and qubits of a quantum computer. This results in a more powerful and efficient system than a classical computer. As explained by Alessandro Curioni, director of the IBM Research Lab in Zurich, “This property of entanglement is very important because it brings a much, much stronger connectivity between the different units and qubits. So the elaboration power of this system is stronger and better than the classical computer.”
In recognition of their contributions to the field of quantum information, the Nobel Prize for physics was awarded this year to three scientists: Alain Aspect, John Clauser, and Anton Zeilinger. Their experiments on entanglement helped to advance the field and demonstrate the potential of quantum computing.
Why do we need quantum computers?
Quantum computers use the principles of quantum mechanics to manipulate quantum bits (qubits), which allows them to perform certain tasks more efficiently than classical computers. One potential application of quantum computers is in the design and discovery of new materials with specific properties. However, there is also a concern that the immense computational power of quantum computers could break the encryption protocols currently used to secure the internet.
To address this concern, it is recommended that organizations and state actors update their cryptography to quantum-safe algorithms that cannot be broken by quantum computers. This is important to prepare for the potential impact of quantum computers on encryption, even though it may negatively affect existing data that hasn’t been encrypted with quantum-safe algorithms.
It is crucial to be aware of the potential impact of quantum computers on security and privacy and take appropriate steps to mitigate these risks. While quantum computers have the potential to bring significant benefits in certain areas, it is important to approach their development and implementation with caution and careful consideration.