Napa · Napa Valley
Visit Quantum Limit with a Private Chauffeur
A 69-acre mountainside ranch at the southern end of the Howell Mountains, with 28 vineyard blocks and views to Mount Diablo, owned by two biophysicists. Quantum Limit does not receive visitors; here is what to know, and a day at sought-after estates nearby that do host.
Book a Six-Hour Wine Tour
About the Winery
Quantum Limit was developed by husband and wife Glenn Rice and Cynthia Hoy, Ph.D. biophysicists who spent their careers discovering and developing FDA-approved drugs. The name comes from quantum physics, where matter at the limit becomes unmeasurable and unpredictable, which they say describes grape growing rather well. They have donated land to the Napa County Land Trust and run the vineyard as net carbon neutral, with solar power.
The 69-acre ranch sits at the southern end of the Howell Mountains in the southeast corner of the Napa Valley AVA, east of Coombsville and south of Atlas Peak, above Wooden Valley. Its 25-acre vineyard is split into 28 hillside blocks of Cabernet Sauvignon and Cabernet Franc between 260 and 900 feet, with views to Mount Diablo and the bay. The winemaking team lists Philippe Melka and Julien Fayard.
Production is under 1,000 cases a year, including the Quantum Limit and Twenty Eight Blocks Cabernets, an Il Maremmano Chardonnay from Carneros and a tiny lot called Entangled, blended with the Lynch-Bages team. Wines are sold on the estate's website, some limited to two bottles per order. The site publishes no visiting program, so Quantum Limit does not receive visitors. The day below goes to nearby estates that do.
Tasting Fees
Quantum Limit does not offer tastings.
Tasting fees as of September 2026. Wineries set and collect their own fees, and they change from time to time.
At a Glance
Location
Napa
AVA
Napa Valley
Visiting
Quantum Limit does not receive visitors; its website publishes no tasting or visiting program, and the wines are sold online.
Known For
Small-lot mountain Cabernet Sauvignon, including Twenty Eight Blocks
Founded
Vineyard developed by Glenn Rice and Cynthia Hoy
Good to Know
Buy through the online shop on quantumlimitvineyards.com; some wines are limited to two bottles per order. Members log in on the website.
A Suggested Six-Hour Day
Pickup at 10:00 a.m. from a nearby hotel such as Silverado Resort or Milliken Creek Inn.
10:00 · Pickup at Silverado Resort or Milliken Creek Inn
Since Quantum Limit does not host visitors, this day takes you to three sought-after estates nearby that do, in Coombsville, Wooden Valley and on the Silverado Trail. Silverado Resort and Milliken Creek Inn are about 12 minutes from the first stop. The day fits about six hours, and extra time can be added by the hour.
10:15 · Covert Estate
About 12 minutes away. A Coombsville estate with an underground winery and Bordeaux-style wines made by Julien Fayard, visited by advance inquiry, one party at a time. Any fee is confirmed when the estate accepts; we allow about 75 minutes.
11:45 · Altamura Vineyards & Winery
About 20 minutes away. A family ranch with caves and a stone winery in quiet Wooden Valley, where the hosted tasting of four estate wines comes with a meat and cheese platter. $75 per person; we allow about 75 minutes. By appointment.
1:20 · Lunch at Angèle
About 20 minutes away. Lunch at Angèle, a French brasserie on the Napa River in downtown Napa, serving lunch daily from 11:30 a.m. to 2:30 p.m. Prefer a picnic? We can arrange a catered picnic at a winery that allows one; the cost is quoted when you book.
2:40 · Seven Apart
About 12 minutes away. A Cabernet house with a mountaintop vineyard on Atlas Peak, hosting a tour of its Base Camp on the Silverado Trail and a seated tasting of the estate Cabernets with paired cheeses, about 90 minutes. By reservation, mainly for allocation members; the fee is confirmed when we book.
4:10 · Back to your hotel
Back by about 4:25 p.m., about six hours after pickup.
About $75 per person in published tasting fees (Altamura), paid directly to each winery; Covert and Seven Apart confirm their fees when we book.
Covert and Seven Apart host by request, and confirm times and fees when they accept. Three wineries is the right pace for a day of serious tasting.
Every tour is custom. This day is a starting point: your chauffeur will shape it around what matters to you, and we plan multi-day tours for guests who want to see more of wine country.
Your Vehicle & Six-Hour Tour Rates
Up to 6 guests
Elite Luxury SUV
Lincoln Navigator or Cadillac Escalade
From $750
Six-hour wine tour, plus 20% gratuity. Additional hours $125 each.
Up to 9 guests
Jet Sprinter or Executive Luxury Van
Captain's chairs and room to spread out
From $1,350
Six-hour wine tour, plus 20% gratuity. Additional hours $225 each.
Larger groups travel in more than one vehicle, and we plan the winery appointments around your group, since many wineries limit groups to 6 to 8 guests. Tasting fees are separate and paid directly to each winery. Every tour starts with six hours; add time by the hour when you book.
Questions
Can you visit Quantum Limit Vineyards?
No. Quantum Limit publishes no tasting or visiting program and sells its wines online, as of September 2026. We can plan a day at nearby estates that do host.
How can I buy Quantum Limit wine?
Through the online shop on quantumlimitvineyards.com; some wines are limited to two bottles per order.
Who owns Quantum Limit?
Husband and wife Glenn Rice and Cynthia Hoy, Ph.D. biophysicists.
Where is the Quantum Limit vineyard?
At the southern end of the Howell Mountains in the Napa Valley AVA, east of Coombsville and south of Atlas Peak, above Wooden Valley.
What does Quantum Limit make?
Under 1,000 cases a year of Cabernet Sauvignon, including Twenty Eight Blocks, plus a Carneros Chardonnay and the tiny Entangled blend.
How does booking a tour with Bien Chauffeured work?
Reserve a six-hour tour online, even if your plans are still taking shape. Your chauffeur will email you first to learn what matters to you, then build your itinerary and make the winery appointments. Extra hours can be added.
Reserve Your Tour Now, Plan the Details Later
Your plans don't need to be final to book. Reserve your six-hour tour online, and your chauffeur will email you first to learn what matters to you, then build your itinerary and make the winery appointments. Prefer to talk? Call our concierge at 888-291-2328.
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