Most of the quantum computing story is told as an opportunity story: trillions of dollars in value, drug discovery, new materials, faster AI. McKinsey & Company's new report, "Three horizons of quantum: A business road map to the future computing economy," tells that story too. Its headline estimate is that quantum computing alone could create $1.3 trillion to $2.7 trillion in economic value worldwide by 2035.
For security leaders, though, the most important point in the report comes early, and the authors call it a double-edged sword. Fault-tolerant quantum computing (FTQC) is the milestone that makes quantum commercially transformative, and it is also what triggers Q-Day: the moment quantum computers can break today's public-key cryptography.
So, as McKinsey puts it, even companies that never use a quantum computer will have to rebuild their security platforms to deal with one.
The report comes from McKinsey's Tech & AI group—Arvind Govindarajan, Henning Soller, Tanguy Catlin, Duc Nam Nguyen, Martina Gschwendtner, and Waldemar Svejstrup—and lays out three development horizons running from today to 2040. Read through a security lens, each horizon carries a different cyber obligation.
McKinsey's central claim is that quantum is arriving sooner than many leaders expected. Vendors are hitting milestones ahead of their own predictions, and the hardware roadmaps are now converging:
IBM has published a path to large-scale fault tolerance by 2029.
IonQ is targeting two million physical qubits by 2030, which would be enough for up to 80,000 logical qubits, the error-corrected units that fault tolerance depends on.
Leading road maps converge on a fault-tolerant machine within five years.
The money is moving too. Equity investment in quantum jumped from $2.5 billion in 2024 to $13.3 billion in 2025. Quantum computing companies passed $1 billion in combined revenue in 2025, and McKinsey projects as much as $4.4 billion by 2028. Horizon Quantum, Infleqtion, Pasqal, Quantinuum, and Xanadu all went public in 2026. Governments have committed $2 billion in the U.S. and more than €1 billion in France, much of it aimed at manufacturing capacity rather than research alone.
Put those road maps next to the U.S. federal crypto timeline. NIST's transition guidance (IR 8547) calls for deprecating RSA-2048 and ECC-256 by 2030 and disallowing them entirely by 2035. If IBM's 2029 target holds, the arrival of fault tolerance and NIST's deprecation deadline land within about a year of each other.
Horizon 1: Early commercialization—and the threat that's already here
McKinsey describes Horizon 1, running from now to about 2030, as the shift from proof-of-concept experiments to paid co-development. Airbus, Boehringer Ingelheim, E.ON, JPMorgan Chase, and Liberty Mutual are all building applications with quantum providers. More than 300 organizations worldwide are already working with quantum technology vendors.
For defenders, Horizon 1 is not a waiting period. The report warns that sensitive data is already exposed to "harvest now, decrypt later" attacks, in which adversaries collect encrypted traffic today so they can decrypt it on Q-Day. Any data that need to stay confidential for longer than the time until a cryptographically relevant quantum computer exists is already at risk.
The report also points to the tools defenders have now:
Postquantum cryptography (PQC): New algorithms built to resist quantum attacks while running on existing hardware. McKinsey says PQC "is here now" and will be critical as companies migrate.
Quantum key distribution (QKD): Uses physics to make interception detectable in real time on protected links, and is starting to move out of the lab.
McKinsey expects the overall quantum communication market to reach $11 billion to $15 billion by 2035. Security is the main reason buyers will spend that money.
Horizon 2: Fault tolerance arrives—and so does Q-Day
Horizon 2, roughly 2030 to 2035, is when McKinsey expects companies to lock in their quantum strategies and start seeing real value. It's also when the security bill comes due.
The report is blunt about what's at stake. Without PQC in place, companies' VPNs, public-key infrastructure, connected devices, and identity systems could all be exposed on Q-Day. For many large enterprises, McKinsey calls Q-Day readiness a "multiyear, multibillion-dollar transformation."
That cost matters in budget discussions. The CFO probably sees quantum as an innovation line item. McKinsey's framing makes it a security infrastructure item too, and one with a non-negotiable deadline.
McKinsey also acknowledges that road maps slip. It names three constraints that could delay fault tolerance:
Manufacturing – Scaling to millions of qubits requires lasers, cryogenics, control electronics, and production capacity that don't yet exist at the needed scale.
Talent – Quantum researchers, engineers, and solution architects remain scarce.
No winning hardware modality – Superconducting, trapped ion, neutral atom, photonic, spin, and topological approaches are all still competing.
Security teams should be careful about treating these as breathing room. Harvest-now-decrypt-later attacks are already happening, so a two-year slip in FTQC doesn't protect data being stolen today. It only changes when that data can be read. NIST's 2030 and 2035 deadlines also don't depend on vendor road maps.
McKinsey also notes something that cuts against a slower timeline: AI is speeding up quantum algorithm design and error correction in ways that could bring fault tolerance sooner. Security teams have had to plan for AI-accelerated attacks. Now they also need to plan for AI accelerating the arrival of Q-Day.
[RELATED: The Next Cyber Crisis Won't Be Just AI, It Will Be Quantum-Enhanced]
Horizon 3: Cybersecurity as a quantum arena
By Horizon 3, around 2035 to 2040, McKinsey expects entire economic arenas to reorganize around quantum capabilities. Of the McKinsey Global Institute's 18 future arenas of competition, cybersecurity is the first of four the report says quantum will affect most.
Its cybersecurity projections:
PQC becomes one of the largest quantum communication verticals, a $2.4 billion to $3.4 billion global market by 2035. McKinsey stresses it is "a multiyear program, not a patch cycle."
QKD reaches $2 billion to $2.8 billion by 2035. By 2040 it could be a standard networking option, with financial exchanges, power grids, hospital systems, and government networks running over shared QKD-protected corridors by default.
McKinsey is careful to point out that QKD's limits are real. It is limited by distance and cannot provide authentication or digital signatures on its own, so it is a complement to PQC, not a substitute. For CISOs, that means the near-term plan is PQC migration, with QKD as an added layer for the highest-value links later.
The report also says quantum could help companies design stronger security systems, which it calls especially important now that AI has dramatically sped up attacks. Quantum is both a threat to current defenses and a possible part of future ones.
The other three arenas also have security implications:
Pharma – Up to $400 billion in value by 2035, eventually including patient-level digital twins, which are some of the most sensitive health data imaginable.
Chemicals and biotech – Up to $800 billion by 2035. Q-CTRL has already shown a 3,000-fold speedup in materials modeling on 120 qubits.
Robotics – "Qubots," robots that use quantum technology in some form, could be a $67 billion industry by 2040. That adds a new class of connected physical endpoints to secure.
Quantum sensing, which McKinsey calls the most mature pillar, is also worth watching. Q-CTRL's magnetic-field navigation sensors have completed safety-of-flight testing as a GPS backup. That's a direct resilience benefit at a time when GPS jamming and spoofing are growing concerns.
McKinsey closes with four priorities for business leaders: secure ecosystem partnerships and access to frontier systems, pilot applications early, build talent and IP, and explore how quantum could ease AI's compute and energy limits. Here's what those mean for a security program:
Inventory your cryptography. You can't migrate what you can't find. Map where RSA and ECC are used across VPNs, PKI, identity, IoT, and third-party connections. This is the security version of McKinsey's warning about building foundations now.
Prioritize long-lived data. Rank data by how long it must stay confidential. Anything valuable past roughly 2030 is a harvest-now-decrypt-later target today.
Budget for multiple years. McKinsey calls PQC readiness a multiyear, multibillion-dollar effort for large enterprises. Funding it as a one-time project sets it up to fail.
Build crypto agility. No hardware approach has won and road maps slip. Systems that can swap algorithms without a rebuild are the best protection against that uncertainty.
Get a seat at the quantum table. If your company is one of the 300+ already working with quantum vendors, security should be part of those partnership decisions from the start, not added at deployment.
Treat QKD as an extra layer, not a replacement. Plan around PQC first, and consider QKD for critical links as the technology matures.
Hold vendors to it. Ask your critical suppliers for their PQC road maps now, before the deadlines arrive.
McKinsey's last line is written for business leaders, but it fits security teams just as well: quantum "will not wait for organizations to feel ready." For security teams, the date that matters most is Q-Day.
Quantum is a popular topic, and it's why it is being covered in a few sessions on the SecureWorld Seattle conference agenda November 4-5.
The Day 1 opening keynote features Jake Hammock, Former CISO, and Assistant CTO for Security and Infrastructure, City of Seattle, talking "Beyond Post-Quantum: QKD, AI Agents, and the Future of Critical Infrastructure Trust." His keynote separates signal from hype and maps where PQC, QKD, AI agents, machine identity, software provenance, and next-generation cyber operations converge, and where they should not be confused.
Later on Day 1, Neha Srivastava, VP, Cybersecurity Product | Quantum & AI Security | Cryptography, JPMorgan Chase & Co., talks "The Quantum Reckoning: From Policy Mandates to PQC Migration Before Q-Day." She presents a practical, engineering-driven framework for helping enterprises transition from policy awareness to operational readiness. Drawing on experience designing and leading cybersecurity programs across fintech, enterprise environments, and critical infrastructure, Srivastava focuses on the organizational, architectural, and governance challenges that determine whether post-quantum migration succeeds.
$1.3T–$2.7T: economic value from quantum computing by 2035
$13.3B: quantum equity investment in 2025, up from $2.5B in 2024
300+: organizations already working with quantum providers
2029: IBM's target for large-scale fault tolerance
33%: share of surveyed quantum adopters spending $10M or more a year on quantum computing (7% spend more than $50M)
$11B–$15B: quantum communication market by 2035
$2.4B–$3.4B: PQC market by 2035
$2B–$2.8B: QKD market by 2035
2040: when QKD could become a standard networking option