How Q-Day Could Potentially Threaten Bitcoin and Your Retirement Savings

My initial encounter with Bitcoin was quite modest. Back in the early 2010s, I heard about Bitcoin from student discussions in university math lectures and occasional news about its use on black markets like the notorious Silk Road. While some peers were enchanted by Bitcoin’s allure, my focus was solely on theoretical physics—Slater determinants, Raman scattering, and Cooper pairs were my true passions. Concepts like “cryptocurrency mining” felt alien to my ambitions. However, as Bitcoin and its security implications started intersecting with my role as a physics journalist, I began to realize how naive my previous attitude had been.

This change in my understanding emerged months ago when a collaboration involving researchers from Google, the Ethereum Foundation, and several universities published a pivotal 57-page paper discussing quantum computers’ threats to cryptocurrency security. I stumbled upon this paper while enjoying breakfast in Queens, NYC. Only an hour and a half after arriving at my office, I comprehended that my life was about to pivot dramatically.

Following that, a second study by Oratomic, a quantum computing startup, sparked a media storm. This document not only highlighted the imminent risks that quantum computers pose but also provided a more aggressive timeline for their potential to disrupt current systems. A critical point in both papers was the estimated number of qubits required to compromise a common encryption standard. Google’s team suggested it could be around 500,000 qubits, while Oratomic estimated a startlingly lower figure of 10,000—close to today’s largest qubit array of 6,100.

Although these qubits are not being used for computation yet, it is beginning to feel like a cryptographic crisis, referred to as “Q-day,” is on the horizon. This crisis would render most existing encryptions that secure our digital transactions and communications obsolete. Consequently, Google urges all stakeholders to transition to post-quantum cryptography (PQC) to avert Q-Day by 2029.

Are quantum computers likely to disrupt cryptocurrency security soon? I reached out to numerous experts to gauge this threat level—focusing not only on Bitcoin but on broader cryptographic concerns. Researchers frequently highlighted Bitcoin as a primary example.

Bitcoin’s encryption relies on the Elliptic Curve Discrete Logarithm Problem (ECDLP), a mathematical challenge that functions as a robust defense against traditional computing attacks. This makes ECDLP widely popular for securing numerous internet transactions, including banking communications and leading cryptocurrencies.

However, researchers have known for almost three decades that sufficiently advanced quantum computers could obliterate this security. They even possess a mathematical formula, Shor’s Algorithm, outlining how to achieve this.

Yet, converting Shor into a functional program for a real quantum machine has proven tricky. Large-scale, error-free quantum computers were non-existent in the ’90s, 2000s, and remain elusive today. Nevertheless, the size estimates for quantum computers necessary to crack ECDLP encryption have been consistently declining. Researchers previously estimated tens of millions of qubits, but as per Oratomic, now it’s just 10,000 qubits.

Google researchers indicate that quantum computers are on the verge of demonstrating their capabilities as potent decryption tools, with implications for blockchain technology—the backbone of cryptocurrencies. They have pinpointed a method for executing an “on-spend” attack, stealing assets transferred during a Bitcoin transaction, which generally takes around 10 minutes.

The underlying message in these studies seemed designed to incite urgency among Bitcoin users, advocating for more serious consideration of PQC. Given Bitcoin’s decentralized structure, protocol modifications require wide-ranging agreement among users.

“I am very concerned but wholeheartedly agree with Google’s findings,” stated crypto pioneer Eli Ben Sasson from StarkWare. A few weeks later, he expressed frustration at the inflexibility of Bitcoin’s development. Similarly, cryptographer JP Ohmason, who contributed to key PQC algorithms, voiced skepticism about the Bitcoin community’s readiness for a post-quantum transition, despite recognizing the potential urgency.

The realms of technology, finance, and information security are all contemplating a shift toward quantum-resistant algorithms and protocols by the end of the 2010s. While Ormason anticipates this transition may extend to 2036 instead of 2029, he stresses that Bitcoin users must act swiftly. “Examining the decision-making speed of the Bitcoin community,” he notes, “it’s clear that urgency is warranted.”

A particularly alarming aspect of the threats against Bitcoin is that its security, like any currency, is as much about perception as it is about technology. “Simply raising awareness that Bitcoin is vulnerable could provoke a market panic,” Ormason cautioned, predicting enormous economic repercussions.

While several proposals exist for enhancing Bitcoin’s security via software updates, implementing them necessitates consensus within the fragmented Bitcoin community. Nearly five years have passed since Bitcoin last attempted such a restructure, and Ben Sasson remarks that discussions around altering Bitcoin’s infrastructure have become contentious. “We find ourselves in a troubling situation where everyone understands what’s needed and acknowledges it isn’t overly complex, yet there’s a pervasive fear in discussing it due to the unpredictable reactions from the sometimes hostile crypto community,” he explained.

Abif Levi, a colleague of Ben-Sasson at StarkWare, has recently developed a method to make Bitcoin quantum-secure without necessitating software updates. However, the computational power needed for each secure transaction would skyrocket business costs by over 200 times.

It’s Everybody’s Concern

The current predicament is a complex web of emerging technologies, advanced mathematics, and human folly. After nearly a decade of filtering out Bitcoin’s commotion, I started questioning whether I should be concerned about these developments. More alarmingly, I found that choosing to avoid blockchain technology won’t shield me from the repercussions of a collision between Bitcoin’s security and quantum computing.

This realization stemmed from my retirement savings. In June 2025, New York Times financial columnist Jeff Sommer reported the unexpected appearance of Bitcoin in his retirement account. It surfaced because his account linked to an index fund that included shares of a company known for holding significant Bitcoin assets. By May 2026, a website called Bitcoin Treasuries ranked this company as the top publicly traded entity owning Bitcoin. Sommer’s findings revealed that major investment firms like Fidelity, Vanguard, BlackRock, and Morgan Stanley included this stock in their funds.

Given that my retirement accounts are managed by Fidelity, any drastic Bitcoin price shifts, driven by quantum fears, could reverberate through the stock of this company, to Fidelity, ultimately affecting my retirement security. In several U.S. states such as California, North Carolina, Texas, and Louisiana, public retirement funds hold stakes in this Bitcoin-related company, emphasizing the wider impact. Additionally, discussions around integrating cryptocurrencies directly into retirement accounts have gained traction, with regulatory changes lurking in the future.

The path forward seems unclear, but fostering collaboration among participants invested in Bitcoin’s future appears crucial. Our society’s progress hinges on such cooperation, and we must acknowledge that future technologies like quantum computing and blockchain need not cloud the importance of consensus. Ben Sasson, a co-author on cryptocurrency literature, advocates for educating users about the implications. Government action—through regulation, penalties, and public awareness—could also facilitate progress.

The current U.S. administration’s stance on cryptocurrency regulation is rather passive, but electoral changes might shift this landscape. Although it’s notoriously tricky for journalists to speculate on future developments, I remain apprehensive about my retirement prospects.