From: mk_thisisit
The creation of quantum computers presents significant engineering hurdles, particularly in scaling them to practical sizes. These challenges are being addressed through continuous research and development.
Error Correction
One of the primary limitations in executing quantum algorithms is the presence of noise and errors [02:23:00]. Current physical qubits are prone to error, with roughly one mistake occurring per 1,000 operations [12:46:00]. This error rate needs to be significantly reduced for reliable universal quantum computers [02:21:00].
Quantum Error Correction
To overcome this, quantum error correction is essential [13:22:00]. This process involves utilizing multiple physical qubits to encode and protect the information of a single “logical qubit” [13:02:00]. By doing so, the error rate can be exponentially reduced [13:12:00]. In 2023, Google demonstrated the creation of a logical qubit that maintained its coherence longer than any physical qubit, proving the viability of this technology [20:33:00]. This breakthrough signifies a revolution, showing that large quantum systems can indeed be managed without succumbing to thermodynamic descriptions that would render them unusable for quantum computation [21:21:00].
Cabling and Connectivity
A major engineering challenge is the sheer volume of cables required to operate quantum computers. Each qubit requires its own steering mechanism and control, currently translating to approximately two cables per qubit [13:55:00]. Scaling to a million-qubit quantum computer, as projected by IQM for 2033 [11:54:00], would necessitate a million cables, which is impractical with current methods [14:06:00]. Companies are actively developing alternative solutions, such as connecting multiple chips rather than having one monolithic chip, ensuring that data transfer between them remains quantum entangled [14:27:00].
Cryogenic Cooling Systems
Quantum computers, particularly those based on superconducting circuits, operate at temperatures very close to absolute zero, specifically around 120 millikelvin (relative to absolute zero) [09:18:00]. This extreme cooling is necessary because at higher temperatures, particles move too quickly, causing unwanted quantum effects [09:27:00].
The majority of a quantum computer’s physical structure, often resembling a large golden fridge, is dedicated to this complex cryogenic cooling system and the necessary cables [15:31:00]. Maintaining this precise temperature and preventing heat transfer from external components, such as receivers or signal synthesis devices, to the quantum chip is critical to preserve the fragile quantum states [15:56:00]. The goal is to cool the system down to a point where only one or two allowed energy levels remain for the qubits to operate effectively [11:02:00].
Cost and Accessibility
The current cost of a 5-qubit quantum computer is approximately one million euros [17:47:00]. While this price is expected to decrease as technology advances and engineering solutions are found [19:04:00], quantum computers are not anticipated to become consumer products for home use [19:29:00]. Instead, they will likely be located in supercomputer centers, accessible to users remotely via the internet through a “quantum cloud” model, similar to how current servers are accessed [19:50:00]. This centralized model addresses the practical challenges of cost, size, and operational complexity.
Other Quantum Computing Technologies
Beyond the superconducting circuits favored by IQM [08:41:00], other technologies for building quantum computers exist, such as cold atoms [08:27:00]. These different approaches each have their own set of engineering challenges and advantages in achieving reliable quantum computation.