Image Citation: [7]
Written by Huyen Nguyen ‘28
Edited by Leopold Li ‘28
The revolution of quantum physics has already changed our lives. A quantum computer harnesses some of the almost-mystical phenomena of quantum mechanics to deliver huge leaps forward in processing power, promising to power exciting advances in various fields [1]. From materials science to pharmaceuticals research, companies are already experimenting with them to develop more powerful batteries for electric cars, transistors for every electronic device we use today, and novel drugs [2]. By taking advantage of quantum physics, fully realized quantum computers would be able to process many massively complicated problems at orders of magnitude faster than modern machines [1]. For a quantum computer, challenges that might take a conventional computer thousands of years to complete might be reduced to a matter of minutes [2].
Understanding a quantum computer’s power lies in its ability to generate and manipulate quantum bits, or qubits [1]. But, what is a qubit, and how does it compare to bits in conventional computers?
Bits are the smallest unit of data that a computer can process and store [2]. Acting as the building blocks of every piece of digital information, a classical bit always exists in one of two states representing 1s or 0s [2]. In other words, these two states can represent either heads or tails of a coin; once measured, the coin takes on the state of either heads (1s) or tails (0s) [3]. Everything from emails to Spotify songs and YouTube videos are essentially long strings of these binary bits, and a chain of transistors are an excellent physical representation of bits [1]. As companies, such as Apple, try to make transistors smaller and smaller over time, the ultimate goal is to fit as many transistors to increasingly smaller devices, such as an iPhone that contains 19 billion 3-nanometer transistors in its main processor chip alone [3]. Despite the reduction in size, it is still limited by the binary nature of the bit [3]. Moreover, the number of transistors on a microchip roughly doubles every two years, signifying exponential growth in computing power; however, there is a physical limit of how small the transistors can be compared to atoms—according to Moore’s Law [4]. Quantum computers, on the other hand, use qubits, which are typically subatomic particles such as electrons and photons [1]. A qubit behaves like a bit and stores either a 0 or 1 (when collapsed), but it can also be a weighted combination of 0 and 1 at the same time [1]. Dating back to the coin analogy, the ability for qubits to be both heads and tails at the same time allows the coin to spin to represent as many positions as possible [5]. However, when a quantum system is measured, its entangled state collapses from being in multiple states at once (or superposition) into a binary state, which can be registered like binary code as either a 1 or 0 (like Schrödinger's famous cat) [5]. When combined with its non-binary nature, two qubits can compute with four pieces of information, three can compute with eight, four can compute with sixteen, and on a larger scale, twenty can compute one million potential values [5]. Groups of qubits in superposition give quantum computers their inherent parallelism, allowing them to process many inputs simultaneously because of the quantum phenomenon of superposition [1]. In the realm of computing, quantum computers stand out for their remarkable abilities.
Due to the fundamentals of quantum mechanics which provides the foundational laws for the entire universe, every system is a quantum system [3]. While conventional computers are also built on top of quantum systems, they fail to take full advantage of the quantum mechanical properties during their calculations [4]. It is more than possible for existing quantum computers to solve math problems in a matter of seconds that would take a conventional computer thousands of years to complete, such as factoring numbers exponentially faster in Shor’s algorithm than any known classical algorithm [4]. So, should we simply replace our computers with new, more advanced quantum computers?
The short answer is no. The major difference between the two computers lies in the mode of transportation analogy [6]. A conventional computer is like a car, capable of quickly navigating familiar roads for everyday tasks, while a quantum computer is like a boat or a submarine in the open sea, able to explore vast, complex areas of information that are difficult for a car to reach [6]. Although it is not an improvement on a car, a quantum computer enables us to navigate previously uncharted and bottomless waters, solving new problems that a conventional computer cannot [6]. Benefits always come with challenges, though. Existing quantum computers can only operate for around one second at a time before the qubits lose their superposition, meaning the error rate is 1 in 100 at worst and 1 in 1,000 at best [3]. The nature of each qubit on its own and its superposition are inherently unstable, so when we combine multiple qubits together, instability will multiply [3]. Furthermore, things based on electron particles that have waves associated with them [1]. When these waves vibrate in unison, coherence takes place; but when falling out of coherence (or decoherence), everything vibrates at a different frequency, creating something called noise [4]. The delicate nature of quantum systems makes them extremely vulnerable to the slightest disturbance, whether that’s a stray photon created by heat, a random signal from the surrounding electronics, or a physical vibration [4]. Reducing the temperature to near absolute zero (about -460 degrees Fahrenheit) alleviates these problems, which tend to destroy the information contained in the qubits [5]. To put this cryogenic temperature into perspective, it is colder than Antarctica (-128.6 degrees Fahrenheit) and even deep space itself (about -455 degrees Fahrenheit) [6]. In order to cool the computer’s quantum chip to milli-Kelvin (mK), IBM built a “super-fridge” called Project Goldeneye that uses a special liquefied helium mix, which is 100 times cooler than outer space [7]. Essentially, quantum computers are not practical in daily tasks, like addition/subtraction that a conventional computer can perfectly perform [8]. So, instead of replacing our everyday laptops, quantum computers are used to enhance floodgates of innovations that our high-performance computers lack.
A challenge today faces is the limitation of what an atom does at a past certain size and how molecules become increasingly difficult to stimulate as they become more complex; this is beyond the reach of high-performance computers [9]. In the quantum world, we must use the language of probability, rather than certainty, representing a feature that provides new levers for more powerful ways to communicate and simulate numerous data [10]. Simulation of nature, for instance, is one of the fundamental floodgates that obeys the laws of quantum physics molecularly [10]. Life is based on molecules, and these molecules are capable of creating diseases, such as cancer [11]. Due to the ambiguity in detecting tumors in their earliest stages, late cancer detection can significantly impact patients’ chances of survival and likelihood of successful treatment [11]. But if we can detect them with quantum computers years before billions of cancer cells spread, when they are just a small colony of a few hundred cancer cells, it is possible to stop their progression and perhaps only rarely will they kill anyone [11]. In addition to enabling end-to-end drug development within a quantum chip, quantum computing has the potential to accelerate the achievement of the 17 Sustainable Development Goals (SDGs) established by the United Nations, from achieving food security through a more efficient nitrogen fixation (SDG 2) to optimizing a large amount of data with many variables to predict extreme weather events (SDG 13) [12]. By accelerating the achievement of the 17 SDGs, quantum computing can provide “a common road map for the peace and prosperity of mankind and earth now and in the future” [12].
The quantum race is already underway, and is predicted to become a multibillion-dollar quantum industry by 2030 [2]. Governments and private investors all around the world are pouring billions of dollars into quantum research and development [2]. IBM, Google, Microsoft, Amazon, and other companies are investing heavily in developing large-scale quantum computing hardware and software [2]. Currently, China has taken the early lead in both the quantity and quality of its research output in the quantum field, committing to at least $15 billion in quantum computing [13]. To maintain its leadership in quantum technology, the Information Technology and Innovation Foundation (ITIF) concludes the United States must take immediate and decisive action, and the report recommends at least $675 million annually for five years [13]. Much of the discourse around quantum computing is about the opportunities it presents in areas such as electric cars, supply chain optimization and chemical research [9]. However, when quantum computers become widely available, quantum computing will challenge modern cryptographic security and whether modern encryption methods will still be sufficient [14]. While working quantum computers capable of breaking today’s security may be a number of years away, major companies like Apple have taken progressive approaches towards post-quantum security with its new iMessage security in the form of the PQ3 protocol [4]. Although many organizations do not need to switch to post-quantum cryptography just yet, a long-lasting strategy can serve not only as a sound basis for ensuring the resilience of people’s services but as of the full potential of a quantum world [2].
Reference:
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Brooks, Michael. “Quantum Computing Is Taking on Its Biggest Challenge: Noise.” MIT Technology Review, 4 Jan. 2024, www.technologyreview.com/2024/01/04/1084783/quantum-computing-noise-google-ibm-microsoft/.
Birch DGW. Apple Introduces Post-Quantum Security — You Should Think About This Too [Internet]. Forbes. Available from: https://www.forbes.com/sites/davidbirch/2024/03/18/apple-introduce-post-quantum-security-you-should-think-about-this-too/
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Swayne, Matt. “Report: China Is Challenging U.S. Leadership in Quantum.” The Quantum Insider, 9 Sept. 2024, thequantuminsider.com/2024/09/09/report-china-is-challenging-u-s-leadership-in-quantum/.
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