THE QUANTUM COMPUTING TECHNOLOGIES COMPETING FOR SUPREMACY

Several distinct types of quantum computer currently compete for supremacy. They're all relatively complex and expensive; several requiring components to be cooled to extreme temperatures approaching absolute zero (-273°C).

This article provides an overview of the main competing technologies - aimed at non-experts - along with a few examples of companies pursuing each technology.

[Our article 'Quantum Intelligence - from GPU to QPU' provides useful context on quantum computing basics and basic building block of these systems - the qubit.]

Note that several other quantum computing technologies exist, that are not covered in this article, including:

• Topological core architecture favoured by Microsoft in the Marjorana series chips,

• Nuclear Magnetic Resonance (NMR) as offered by SpinQ

• As well as XeedQ's diamond spin qubits

We've focused here on providing a concise, generalist's overview. For those interested in more comprehensive market intelligence, data (including our quantum computing knowledge graph) or bespoke research / reporting - please contact us directly.

SUPERCONDUCTING QUANTUM COMPUTERS

The most widely recognised quantum computing technology - in simple terms:

• Tiny circuits are created from superconducting material (eg. niobium or tantalum), using techniques similar to traditional semiconductor fabrication

• The circuits are cooled (eg. with a dilution refrigerator) close to absolute zero (-273°C), so that they effectively provide no electrical resistance and limitless conductivity

• Precise microwave pulses are then fired at these circuits

• Qubit states are measured according to interaction of the microwaves with the circuit (eg. changes in frequency or phase)

What many of us recognise visually as a quantum computer is often actually the dilution refrigerator, used to cool down small circuits. In some systems these circuits are constructed of materials that have superconducting properties when chilled to absolute zero (-273°C)

Strengths:

• Fast operation speeds (nanoseconds) and precise control, commercially available and backed by significant corporate investment

Weaknesses:

• Extreme cooling requirements, noise sensitivity, large physical footprint (potentially data centre scale for single useful quantum computer), high power consumption; est. 160MW for 4,000 logical qubit system [1]

Companies pursuing the technology include(d) but are not limited to:

🇨🇳 Alibaba Quantum Lab - 'donated' to Zheijang University in 2023 | 🇫🇷 Alice&Bob

🇺🇸 Amazon Web Services | 🇨🇳 Baidu Quantum Computing Institute - 'donated' to Beijing Academy of Quantum Information Sciences (BAQIS) in 2023 | 🇯🇵 Fujitsu | 🇺🇸 Google Quantum AI Lab | 🇺🇸 IBM | 🇺🇸 Rigetti | 🇨🇳 Tencent

TRAPPED ION QUANTUM COMPUTERS

Another leading approach involves trapping ions, in simple terms:

• Charged atomic particles - ions - (eg. of beryllium, calcium, ytterbium) are suspended in a vacuum chamber using electromagnetic fields

• Precisely tuned lasers are used to cool the ions, reducing their motion

• The ions are then manipulated (the qubits in this system) with laser or microwave pulses to change their state

• The changed qubit quantum states can be measured by detecting fluoresence - ions in one state emit photons, others remain dark

An ion trap for quantum computing from 2011

Strengths:

• Coherence times of minutes vs microseconds, fully connected qubits, high fidelity

Weaknesses:

• Slower operations (vs superconducting systems), complex engineering to scale, physical space requirements (potentially tennis court sized usable quantum computer), high power consumption; est. 140MW for 4,000 logical qubit system [1]

Companies pursuing the technology include but are not limited to:

🇦🇹 Alpine Quantum Technologies (AQT) | 🇫🇮 IonQ | 🇬🇧/🇺🇸 Quantinuum

SILICON / SI-BASED / SILICON SPIN QUANTUM COMPUTERS

An emerging approach that leverages existing semiconductor fabrication infrastructure:

• Qubits are derived from the quantum spin states of individual electrons (or atomic nuclei) trapped within a silicon structure (eg. chip)

• The silicon chip is cooled near to absolute zero (-273°C)

• The quantum state of the electrons or nuclei are precisely altered with electromagnetic / microwave pulses or via electrical gates

• Qubit states are measured by detecting the electric signal impact of induced changes on adjacent electrons

Intel's 'Tunnel Falls' silicon spin qubit chip from 2023

Strengths:

• Make use of existing semiconductor foundry capacity, small physical size, modest cooling requirements, low power consumption; est. 0.4MW for 4,000 logical qubit system [1]

Weaknesses:

• Few demonstrated qubits at present (earlier stage technology), challenging qubit control, short coherence time, challenge to maintain uniform qubit quality across large chips

Companies pursuing the technology include but are not limited to:

🇦🇺 Diraq | 🇮🇪 Equal1 | 🇺🇸 Intel | 🇫🇷 Quobly | 🇦🇺 Silicon Quantum Computing

LINEAR OPTIC / PHOTONIC QUANTUM COMPUTERS

Linear optic or photonic quantum computers use light particles - photons - as qubits. One big advantage over other approaches is the ability to process quantum information at room temperature:

• Generate photons, commonly with a specialised laser light source (eg. nonlinear crystal or quantum dot lasers)

• Direct these photons through optical circuits eg. with mirrors, along fibre optic cables or through microscopic light channels in specialised chips

• Quantum information is encoded in properties of the photons, such as the direction of light waves (polarisation)

• The electromagnetic fields of the photonic cubits (pulses of light) can then be measured to determine their state eg. with highly sensitive (room temperature) photo-detectors

Strengths:

• Operate at higher temperatures vs superconducting systems, natural integration with communications systems (eg. through fibre optic cabling), minimal decoherence of photons

Weaknesses:

• Error correction challenging, potentially significant physical space requirements (small data centre scale for useful quantum computer), high power requirements; est. 100MW for 4,000 logical qubit system [1]

Companies pursuing the technology include but are not limited to:

🇬🇧 Aegiq | 🇨🇳 Bose Quantum Technology | 🇺🇸 Psi Quantum | 🇫🇷 Quandela | 🇨🇦 Xanadu

NEUTRAL ATOM QUANTUM COMPUTERS

Most similar to trapped ion architectures, neutral atom quantum computers commonly involve:

• Trapping atoms (eg. of caesium, rubidium, strontium or ytterbium) with lasers and electromagnets in magneto-optical traps / with optical tweezers of focused laser beams - these become the qubits of the system

• The atoms are then cooled to extremely low temperatures (with lasers) to reduce motion, then excited with pulses of laser light to encode quantum information

• Qubits are entangled by energising them temporarily to Rydberg states - pushing electrons to far-out orbits

• Qubit states are then inferred by detection of fluorescence when atoms are illuminated under specific frequencies of laser light

A 103 nm particle (the tiny, bright dot) trapped by an optical tweezer

Strengths:

• All-to-all qubit connectivity, every atom / qubit identical, moderate physical space requirements, moderate power requirements; est. 4MW for 4,000 logical qubit system [1]

Weaknesses:

• Complex laser and vacuum systems, control system scaling challenges, slower gate operations vs other system architectures

Companies pursuing the technology include but are not limited to:

🇺🇸 Atom Computing | 🇺🇸 Infleqtion | 🇫🇷 Pasqal | 🇺🇸 QuEra Computing

QUANTUM COMPUTERS WITH ELECTRONS ON HELIUM

A niche approach that we are only aware of one commercial company - EeroQ - pursuing:

• Float electrons on liquid helium

• Quantum magnetic (spin) state of each electron is measured, forming a qubit

• Electrons trapped in micro channels cut into silicon wafers

EeroQ's 'electrons on liquid helium on silicon approach to quantum computing

Strengths:

• Relatively simple structure, promise of long coherence times, similarity to silicon approach; use of silicon semiconductor foundry infrastructure, low physical space requirements

Weaknesses:

• Early stage, cooling requirements unclear, microchannel engineering challenges, limited data on scaling potential / commercial viability

Companies pursuing the technology include but are not limited to:

🇺🇸 EeroQ (Chicago)

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For further insights into the quantum computing market derived from Osinto's growing quantum knowledge graph, please contact us directly.

Sources:

[1] An Economic Analysis of Quantum Computing [ICM, April 2025]

Harnessing The Power Of Neutrality: Comparing Neutral-Atom Quantum Computing With Other Modalities [Quantum Insider, February 2024]

QBI: Quantum Benchmarking Initiative [DARPA, accessed April 2025]

Electron-on-helium qubit [Wikipedia, retrieved April 2025]

EIFO invests in more quantum technology [ EIFO, June 2024]

What Types Of Quantum Computers Exist In 2024? [ Quantum Insider, June 2023]

Introduction to quantum computing [Microsoft, accessed April 2025] What is Quantum Computing? [AWS, accessed April 2025]

A Practical Quantum Computer Is Coming! But When? [CNBC, March 2025] What is Quantum Computing? [UKRI national Quantum Computing Centre, accessed April 2025] What is quantum computing? [McKinsey & Company, March 2025] Quantum computing: What leaders need to know now [MIT Sloan, January 2024] Quantum Computing On Track to Create Up to $850 Billion of Economic Value By 2040 [Boston Consulting Group, July 2024]